REGIONAL ASSESSMENT OF GROUNDWATER VULNERABILITY TO CONTAMINATION

Document Sample
REGIONAL ASSESSMENT OF GROUNDWATER VULNERABILITY TO CONTAMINATION Powered By Docstoc
					                REGIONAL ASSESSMENT OF GROUNDWATER
             VULNERABILITY TO CONTAMINATION IN GAZA STRIP
                                                                                                                                                                  Mohammad N. Almasri, PhD
                                                                                                                                                              Water and Environmental Studies Institute
                                                                                                                                                           An-Najah National University, Nablus – Palestine
                                                                                                                                                                        mnmasri@najah.edu

 INTRODUCTION. Gaza Coastal Aquifer (GCA) is the major source of fresh water for the 1.4 million residents of Gaza Strip. The aquifer is under
 deteriorating quality conditions due mainly to the excessive application of fertilizers. As part of the efforts to restore the aquifer’s water quality, it was
 decided to introduce protection alternative measures that address the non-point sources of pollution in the aquifer. The first step in proposing and
 developing efficient protection alternatives is through the spatial assessment and evaluation of groundwater vulnerability to contamination. This
 assessment points out the areas of high priority that can be easily contaminated and thus agricultural activities and wastewater disposal can be controlled,
 minimized, or even banned. The well-known DRASTIC method was applied to compute the vulnerability of GCA to contamination. We utilized GIS spatial
 capabilities to prepare, arrange, process, and manage the data pertaining to the DRASTIC method. The final output from the DRASTIC method is a map
 showing the spatial distribution of the intrinsic vulnerability values and the corresponding qualitative indices for GCA.

GROUNDWATER VULNERABILITY. The tendency or likelihood                                                                                                                                                                                   DRASTIC METHOD. Developed by the US EPA to be a standardized system for
for contaminants to reach a specified position in the groundwater                                                                                                                                                                       vulnerability evaluation and thus became the most widely used groundwater
system after introduction at some location above the uppermost                                                                                                                                                                          vulnerability mapping method. DRASTIC is named for the seven factors considered
aquifer. Thus, groundwater vulnerability assessments look for to                                                                                                                                                                        in the method: Depth to water, net Recharge, Aquifer media, Soil media,
establish the relationship between land use activities and                                                                                                                                                                              Topography, Impact of vadose zone media, and hydraulic Conductivity of the aquifer.
groundwater contamination in order to develop policies and                                                                                                                                                                              Each of these factors is assigned a rating from one to ten based on a range of
programs to preclude groundwater contamination.                                                                                                                                                                                         values. The ratings are then multiplied by a relative weight ranging from one to five.

                                                                           SELECTED PARAMETERS FOR THE DRASTIC METHOD
            A n-N ajah N atio na l Un ive rsity                                                                                      A n-N a jah N a tio na l Un ive rsity                                                                                                                             An-Najah National University
                                                                                                                                                                                                                                                                                                                                                                                                                       A n-Naja h Nat ional U niversity
                                                                                                   40




                                                                                                                                                                                                                                                                                                  Water and Environmental Studies Institute
    W ater and Env iron m ental Stud ies Institu te                                                                          W a te r a nd Env iron me nta l Stud ie s Institu te                                                                                                               Layout preparer: Mohammad N. Almasri, PhD                                                                       W ater and Env iron m ent al Studi es Ins titute
  La yo ut pre pa rer: M oh am m ad N . A lm asri, P hD                                                                    La yo ut pre pa re r: M oh am ma d N . A lm asri, P hD                                                                                                                      N                                                                                                      Layo ut prepa rer: M o ham mad N. Alm as ri, P hD
                                                                                         10




                                                                                                                                                                                                                                                                                                                   1 0 1 2 Kilometers
                                                                                                         60
                                                                                              50




                                                                                                                                                                                                                                                                                                   W       E
         N                                                                                                                      N                                                                                                                                                                                                                                                                                  N
                                                                                                                                                                                                                                                                                                       S
                               1 0 1 2 Kilom e te rs                                                                                               1 0 1 2 Kilom eters                                                                                                                                                                                                                                                                    1 0 1 2 Kilom eters
                                                                                                        50
                                                                                          60




     W       E                                                                                                             W         E                                                                                                                                            REGIONAL ASSESSMENT OF GROUNDWATER                                                                                          W        E
                                                                                    10




                                                                                                                                                                                                                                                                                    VULNERABILITY TO CONTAMINATION
         S                                                                                                                      S                                                                                                                                                             IN GAZA STRIP                                                                                                        S

                                                                                     50                           80
                                                                           20




R EG IO N A L AS SES SM E N T O F G R O UN D W A TE R                                                                  R EG IO N A L AS SES SM EN T O F G R O UN D W A TE R                                                                                                                                                                                                                             REG ION AL ASS ESS M ENT OF G RO UNDW A TER
                                                                          0




   V U LN ER A B IL IT Y T O C O NT A M INA TIO N
                                                                                                             70           V U LN ER A B ILITY TO C O NT A M INA TIO N                                                                                                                                                                                                                                     VULN ERA BILITY TO CO NTAM INA TIO N
                                                                                         50


                                                                                                 70

                                                                                                 60
                                                                      10




                  IN G A ZA S TR IP                                                                                                      IN G A ZA S TR IP                                                                                                                                                                                                                                                             IN GAZA S TR IP
                                                                               40
                                                                                               50
                                                                     0




                                                                                                   50
                                                                               40


                                                                                          0
                                                                                     60 7
                                                                     20




                                                           0
                                                                                60
                                                           10
                                                      20




                                                                          30
                                                 0




                                                0               20
                                                                     50
                                                      30




                                                            60
                                                           70




                                  0
                                10
                                                      60
                                                40
                                                      70




                     0
                                      50
             0




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     Gaz a S trip
                                 70




                         60
                                                80




                                                                    Gaza Strip
                                                      90




                                                                    Contours of d epth to w ater table (m)
                                                               Depth to water table (m )
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               Slope of ground surface
                                                                                                                                                                                                                                                                                                                                                         Soil type
                                                 70                                                                                                                                                                                                                                                                                                                                                                                                                                                  0 - 3.437
                                 60




                                                                         0 - 1.524                                                                                                                                                                                                                                                                              Dark brown / reddish brown
                         60




                                                                    1.524 - 4.572                                                                                                          G az a S trip                                                                                                                                                        Loess soils                                                                                                                          3.437 - 6.874
                                           60




                                                                    4.572 - 9.144                                                                                                   G ro un d w ate r rec ha rg e (m /ye ar)
                                                                                                                                                                                                                                                                                                                                                                Loessal sandy soil
                     70




                                                                    9.144 - 15.24                                                                                                          0 - 0 .25                                                                                                                                                                                                                                                                                                 6.874 - 10.312
                                 80




                                                                    15.24 - 22.86                                                                                                          0.2 5 - 0 .5                                                                                                                                                         Sandy loess soil
                                                                    22.86 - 30.48                                                                                                          0.5 - 0.7 5                                                                                                                                                          Sandy loess soil over loess                                                                                                          10.312 - 13.749
                                                                    30.48+                                                                                                                 > 0 .7 5                                                                                                                                                             Sandy regosols
                                                                    No D ata                                                                                                               N o D a ta                                                                                                                                                           Gaza Strip                                                                                                                           No D ata



         GROUNDWATER VULNERABILITY MAP AND CORRESPONDING ANALYSIS
                                                                                                                                                                                                                                                                                                           80%                                                                                                 1080
                 N                                                                                                                   N

                                                                                                                                                                                                                                                                                                                                                                                                                  960                                                                                                    Q1                                    Mean
         W               E                                                                                                     W             E

                                                                                                                                                                                                                                                                                                                                                                                                                  840                                                                                                    Min                                   Max
                                                                                                                                                                                                                                                                                  Percentage of area




                 S                                                                                                                   S
                                                                                                                                                                                                                                                                                                           60%
 2       0           2        4 Kilo me te rs                                                                          2        0        2       4 Kilo m e te rs                                                                                                                                                                                                                                                 720                                                                                                    Median                                Q3
                                                                                                                                                                                                                                                                                                                                                                                                NO3 (mg/L)




                                                                                                                                                                                                                                                                                                                                                                                                                  600
                                                                                                                                                                                                                                                                                                           40%
                                                                                                                                                                                                                                                                                                                                                                                                                  480
                                                                                                                                                                                                                                                                                                                                                                                                                  360
                                                                                                                                                                                                                                                                                                           20%
                                                                                                                                                                                                                                                                                                                                                                                                                  240
                                                                                                                                                                                                                                                                                                                                                                                                                  120
                                                                                                                                                                                                                                                                                                               0%
                                                                                                                                                                                                                                                                                                                                                                                                                       0
                                                                                                                                                                                                                                                                                                                                      Low                Moderate               High
                                                                                                                                                                                                                                                                                                                                                                                                                                              Low                                              Moderate                                               High
                                                                                                                                                                                                                                                                                                                                              Qualitative vulnerability Index                                                                                    DRASTIC qualitative index


                                                                                                                                                                                                                                                                                                       280                                                                                                     190                  Q1                M ean                    M in                       M ax                     M edian                                        Q3
                                                                                                                                                                                                                                                                                                                                                Q1            Mean                                             180
                                                                                                                                                                                                                                                                                                       240                                      Min           Max                                              170

                                                                            G a za S tr ip                                                                                                                                                                                                                                                                                                                     160
                                                                                                                                                                                                                                                                                                                                                                                              DRASTIC index




                                                                                                                                                                                                                                                                                                       200                                      Median        Q3
                                                                                                                                                                                                                                                                               N loading (kg)




                                                                                                                                                                                                                                                                                                                                                                                                               150
                                                                     D R A S T IC in d e x                                                                                                                                                                                                             160
                                                                                                                                                                                                                                                                                                                                                                                                               140
                                                                                                                                                                                                                                                                                                                                                                                                               130
                                                                            80 - 100                                                                                                                                                                                                                   120                                                                                                     120
                                                                                                                                                                                                                                                                                                                                                                                                               110
                                                                            100 - 120                                                                                                           G az a S trip                                                                                              80                                                                                                  100
                                                                                                                                                                                         D R A S T IC qu a lita t iv e in d e x                                                                                                                                                                                 90
                                                                            120 - 140                                                                                                           Lo w                                                                                                       40                                                                                                   80
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       Open area
                                                                                                                                                                                                                                                                                                                                                                                                                           Almond




                                                                                                                                                                                                                                                                                                                                                                                                                                              Dates




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    Vegetables
                                                                                                                                                                                                                                                                                                                                                                                                                                                        Grapes
                                                                                                                                                                                                                                                                                                                                                                                                                                     Citrus




                                                                                                                                                                                                                                                                                                                                                                                                                                                                 Greenhouses




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 Olives




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    Settlements
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 Built-up
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                Horticulture




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          Fruits
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           Field crops




                                                                            140 - 160                                                                                                           M od e r ate
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            areas




                                                                                                                                                                                                                                                                                                               0
                                                                                                                                                                                                H ig h
                                                                            160 - 180                                                                                                           N o D a ta
                                                                                                                                                                                                                                                                                                                                  Low                    Moderate               High

                                                                                                                                                                                                                                                                                                                                                DRASTIC qualitative index




OUTCOME. Based on the vulnerability analysis, many                                                                                                                                                                                                                                                                                            CONCLUSION. 10% and 13% of                                                   CONCLUSION. It is difficult to get
                                                                                                                                                                                                          N                                               N


                                                                                                                                                                                                  W               E                               W               E


                                                                                                                                                                                                          S                                               S

                                                                                                                                                                                              2       0       2       4 Kilo me te rs         2       0       2       4 Kilo me te rs

management options can be designed such as:                                                                                                                                                                                                                                                                                                   Gaza Strip is under low and high                                             a conclusive relationship between
[1] Managing the amount, type, and timing of nitrogen                                                                                                                                                                                                                                                                                         vulnerability of groundwater                                                 land use classes and vulnerability
application especially in the moderate and high vulnerability                                                                                                                                                                                                                                                                                 contamination, respectively while                                            indices. However, except for the
areas. Threshold values should be considered when designated                                                                                                                                                                                                                                                                                  more than 90% of Gaza Strip is                                               Field crops land use area, the first
areas that will be targeted by the management options. Areas                                                                                                                                                                                                                                                                                  under moderate vulnerability.                                                quartile (Q1) of the DRASTIC
decrease with increasing threshold value;                                                                                                                                                                 N                                               N
                                                                                                                                                                                                                                                                                                                                                                                                                           indices are within the moderate
[2] Setting up realistic crop yield goals and crediting nitrogen                                                                                                                              2
                                                                                                                                                                                                  W




                                                                                                                                                                                                      0
                                                                                                                                                                                                          S

                                                                                                                                                                                                              2
                                                                                                                                                                                                                  E




                                                                                                                                                                                                                      4 Kilo me te rs         2
                                                                                                                                                                                                                                                  W




                                                                                                                                                                                                                                                      0
                                                                                                                                                                                                                                                          S

                                                                                                                                                                                                                                                              2
                                                                                                                                                                                                                                                                  E




                                                                                                                                                                                                                                                                      4 Kilo me te rs
                                                                                                                                                                                                                                                                                                                                              CONCLUSION. Results show                                                     vulnerability zones while for the
from sources other than commercial fertilizers;                                                                                                                                                                                                                                                                                               that the highest first quartile,                                             median for the DRASTIC indices
[3] Fertilizer applications should be applied at the period of                                                                                                                                                                                                                                                                                median, mean, and third quartile                                             for the land use areas of Grapes,
maximum crop uptake.;                                                                                                                                                                                                                                                                                                                         nitrate concentrations are                                                   Horticulture, and Olives are within
[4] Split applications of nitrogen-based fertilizers;                                                                                                                                                                                                                                                                                         reported in the high vulnerability                                           the high vulnerability zones.
[5] The use of nitrification inhibitors to reduce the mass of                                                                                                                                                                                                                                                                                 zone. However, maximum nitrate
nitrate in the soil; and                                                                                                                                                                                  N                                               N
                                                                                                                                                                                                                                                                                                                                              concentration is encountered in                                              CONCLUSION. Results show that
[6] Land use change. One of the common management                                                                                                                                                                                                                                                                                             moderate vulnerability zone.
                                                                                                                                                                                                  W               E                               W               E




                                                                                                                                                                                              2       0
                                                                                                                                                                                                          S

                                                                                                                                                                                                              2       4 Kilo me te rs         2       0
                                                                                                                                                                                                                                                          S

                                                                                                                                                                                                                                                              2       4 Kilo me te rs                                                                                                                                      the highest median on-ground
alternatives in order to reduce groundwater pollution from the                                                                                                                                                                                                                                                                                There is no conclusive                                                       nitrogen loading correlates well
on-ground activities is to make changes in the land use cover.                                                                                                                                                                                                                                                                                relationship between nitrate                                                 with the areas characterized as of
Such changes involve developing land uses that are more prone                                                                                                                                                                                                                                                                                 concentration in GCA and the                                                 low vulnerability of groundwater to
to produce nitrate leaching to groundwater.                                                                                                                                                                                                                                                                                                   vulnerability indices.                                                       contamination.



                                                                             UNESCO/Flanders FIT Project                                                                                                                                                                                                                                                  This research was conducted under
                                                                     Capacity Building and Training on Environmental                                                                                                                                                                                                                                          grant number 513RAB2041
                                                                               Training and Management

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:5
posted:11/3/2011
language:English
pages:1