Using IMDPA Model for Mapping Groundwater Degradation in Iran

Transcription

1 Using IMDPA Model for Mapping Groundwater Degradation in Iran H. Khosravi 1 Gh. Zehtabian 2 H. Ahmadi 3 H. Azarnivand 4 1. PhD Student, Faculty of Natural Resources, University of Tehran, hakhosravi@ut.ac.ir 2. Professor, Faculty of Natural Resources, University of Tehran, Iran 3. Professor, Islamic Azad University 4. Associate Professor, Faculty of Natural Resources, University of Tehran, Iran Abstract Today water resources degradation is one of the most important desertification factor in arid and semi-arid regions which is caused by mismanagement and improper practices of human, especially in the agriculture sector. The aim of this study is investigation of groundwater criterion in desertification condition of Kashan region, Iran and finally preparing groundwater degradation map. The study area is about ha and, It is located in 33º 52 to 34º 20 N and 51º 06 to 51º 33 E. At the first, among different existing methods, IMDPA model was selected and the intensity of ground water quality was evaluated on the basis of 5 parameters including groundwater table decrease, Cl concentration, water shortage for wildlife, EC, water crisis index. According to the factorial scaling technique, score-ranging from 1(good condition) to 2(deteriorated condition) is assigned to each index. Finally the value number map of groundwater degradation was obtained as geometric average of single indices according to the formula: Index _ xij = (layer_ 1ij). (layer_2ij)... (layer_nij) 1/n ;Where: Index-X: groundwater criteria, Layer: Index of groundwater criteria and N: number of indices. The results showed that 40.3 percent of study area was found to be in high class and 59.7 percent in very high class of degradation. Studying the mean weight of numerical value, it is distinguished that the intensity of ground water degradation for the total area is 1.74 which is classified under very high class of degradation. KEYWORD: Groundwater, Degradation, IMDPA Model, Index, Kashan. 1

2 Introduction There are vast natural areas in Iran, which have susceptible and fragile ecosystem and desert condition. According to the new definition of desert, except a narrow strip in north of Iran, other parts of the country encounter desertification problem. There are about 50 million hectares desert lands in Iran and 120 million hectares are also desert-pore regions. Wind and water erosion are two major factors of land degradation in these regions, which deliver and deposit about 3 billion m 3 of eroded sediments into reservoirs, rivers and lowlands. Moreover, soil erodibility, improper agriculture and irrigation systems as well as inappropriate application of manure and pesticides increase primary and secondary salinity, which are promoting factors of desertification. It also should be noticed that about 50% of 15 million ha of agricultural lands in Iran have salinity problem. Ground waters depletion because of increased exploitation and salt/fresh waters imbalance has decreased waters quality for different uses. These factors in addition to misuse of resources have increased soil degradation while decreased production and biomass. Along with human factors, deforestation, landuse change, small size of farmlands, poverty, population and finally illiteracy are among others parameters with affect on desertification. Over last 30 years many activities have preformed to establish sand dunes and prevent desertification which has preserved threaded towns and village by developing biologic measures such as increase of vegetation cover. Also, more than 2 million ha were afforested and another program is undertaken for 5 million ha. Since various factors are responsible for desertification, it is necessary to determine relevant criteria and indices for desired land uses as well as for desertification control. To achieve the above mentioned objective and based on review of international/national desertification models in literature, groundwater criteria and 5 indices were selected which quantitative and weighted values of these factor determine groundwater degradation intensity of each region. Consequently, groundwater intensity map was classified. It is expected to calibrate the IMDPA model for mapping groundwater degradation intensity map in arid, semi-arid, and humid semi-arid regions of Iran which will ease decision making and recommendations for desertification control activities. It is also expected to share these expenses with other country for expand global knowledge about the phenomena. Materials and Method Study Area Kashan is located in 51 27' E and 33 51' N and has an arid climate with annual average precipitation of mm. This region is in Isfahan province and south of Tehran with mean annual temperature of 18.8 C. 2

3 Figure-1 Location of the study area in Isfahan province and Iran Methodology The risk of groundwater degradation in Kashan region was evaluated on the basis of 5 regional indices including: groundwater table decrease, Cl concentration, water shortage for wildlife, EC, water crisis index. Following the factorial scaling technique, to each of indicator is assigned a score ranging from 1 (good conditions) to 2 (deteriorated condition). Value "zero" is assigned to the areas where the measure is not appropriated and/or those, which are not classified. The classes and the scores are based on the influence that various parameters have on the land degradation processes. In the most cases, the function representing the variation of the indicators (score) is liner ranging between the extreme values [1-2], although, in some particular cases, a non-linear variation is possible. Areas such as ponds urban land, etc were attributed zero but, since urban area development is considered as a factor of desertification in Iran, so it was studied in a separate part of management field as technological desertification and finally a map was provided for anyone of valued indices. Finally the value of groundwater criterion was obtained as geometric average of scores of single indices according to the formula: 1/ n Index X ( Layer 1).( layer 2)...( Layer n) Where: Index-X: A given criteria Layer: Index of each criterion N: number of indices for each criterion In the end, five maps were provided that they were used to study indices qualities and their influence on desertification trend, and the final map indicating groundwater degradation status of 3

4 this region was provided using geometric mean of mentioned criteria based on the following formula: Ground water quality: (groundwater table decrease x CL concentration x water shortage for wildlife x EC x water crisis index) 1/5 The risk of water ground degradation in the final map was classified in 4 subtypes according to the table1. Table-1 Classification of desertification intensity in kashan region Low Medium High Very High Results Table2 shows indices used to evaluate recent desertification condition and chosen to study ground water resources in Kashan region. Table-2 resourced degradation indices Index Class Low Medium High Very high (a) Very high (b) Value Groundwater table decrease >50 (cm/year) Quality of water EC (µmhos/cm) < >5000 CL (Mgr/liter) < >3000 resources shortage for people and lives tocks The Index of Sustainable Development Committee of International Union resources is enough resources is reasonably enough to resources meets live stock and needs, proportionality resources is less than resources is much less than 10 >I UN 10<IUN< 20 20<IUN<40 40<IUN<60 60<I UN After studying mean value of factors involved in water resources deterioration, it s indicated that water crisis index is the most effective factor in increasing groundwater degradation intensity of studied region. In general, we can introduce the following table for all indices influencing water resources deterioration. 4

5 Table-3 Geometric average of the quantitative values of water resources degradation index Order Index Value Class 1 Groundwater table decrease Very high 2 EC (µmhos/cm) Very high 3 CL (Mgr/liter) High 4 resources shortage High 5 The Index of development permanent committee of 1.83 Very high Figure-2 Characterization of the sensitive areas to groundwater degradation in Kashan Discussion and Conclusion It s evident with respect to the map of water resources desertification: % of total area is classified as highly deteriorated water resources. This class is more observed in NW, west, SW of Kashan % of total area is classified as very highly deteriorated water resources. This class is more observed in NW, E, and SE of Kashan. Studying the mean weight of numerical value, it is distinguished that the intensity of ground water degradation for the total area is 1.74 which is classified under very high class of degradation. Initial results provided by this study for determining effective indices and criteria on desertification showed that both environmental and anthropogenic factors play significant t role 5

6 in desertification. As an example in Kashan region the most important factor in desertification is water resources degradation. This is mainly because of better access to groundwater resources, intensive population and numerous wells in plain areas. Other effective factors, which should be mentioned, are surface water harvesting projects to supply water demands for domestic, industrial and agricultural uses. Such managerial factors increase the role of anthropogenic activities in desertification intensity more than environmental parameters. According to the current definitions, desertification is a global problem and needs a global action to control it on the basis of research and experiences of different countries. Acknowledgment Funding for this research was provided by the project of Desertification Atlas of Iran. We would like to extend our appreciation for the assistance and collaboration of the head of project Prof. Gholamreza Zehtabian References 1. Basso F, Belloti A, Faretta S, Ferara A, Manino G, Pisante M, Quaranta G, Tabemer M., The Agri Basin In: MEDALUS Project_ Mediterranean Desertification and Land Use. Manual on Key indicators of desertification and mapping Environmentally Sensitive areas to desertification. 2. European Commission, Mediterranean Desertification and LandUse MEDALUS). MEDALUS Office, London. 3. FAO/UNEP, Provisional Methodology for Assessment and Mapping of Desertification, Rome. 4. FAO-UNEP/ UNESCO/ WMO, Word Map of Desertification at a Scale of 1: Giordano L., F. Giordano., S. Grauso, M. Lannetta, M. Scicortino, G. Bonnati, F. Borfecchia., Desertification vulnerability in Sicily. Proc. Of the 2 nd Int. Conf. On New Trend in and Environmental Engineering for Safety and Life: Eco-Compatible Solution for Aquatic Environments. 6. Grumblat, J., Kenya Pilot Study to Evaluate FAO/UNEP Provisional Methodology for Assessment and Mapping of Desertification (Gok, DRSRS). 7. Kosmas C, Gerontidis St, Detsis V, Zafiriou Th, Marathianou M., Application of the MEDALUS methodology for defining ESAs in the Lesvos Island, European Commission. Capri, Italy, June 24-28, Khosravi H, The Strategies for Prevention of Desert Regions Degradation Using Desertification Models in Kashan, the forth international Iran and Russia conference "Agriculture and Natural Resources" Shahrekord, Iran. 9. Khosravi. H, Gh. Zehtabian, M. Ghodsi, The study of water erosion effect on desertification intensity in Kashan region, The First European Conference of Iranian Scientists in Agriculture and Natural Resources, 8-9 October, Paris, France. 10. Khosravi. H, Gh. Zehtabian, H. Ahmadi, H. Azarnivand, 2010, Quantitative Evaluation of Ground Degradation in Order to Presentation a Regional Model (Case Study: Kashan, Iran), 30th EARSeL Symposium. Remote Sensing for Science, Education, and Natural and Cultural Heritage. 31th May - 3rd June 2010 UNESCO Headquarters, Paris, France. 11. Khosravi. H, Gh. Zehtabian, M. Ghodsi, 2009, Effective Factors in Land Degradation in Kashan Region, Iran, International Workshop on Urbanization, Land Use, Land Degradation, and Environment, 28 Sept-01 Oct, Denizli Turkey. 12. Kosmas C, Kirkby M, Geeson N, European Commission of MEDALUS Project Mediterranean Desertification and Land Use. 13. Ladisa G, Todorovic M, Trisorio_liuzzi G, Characterization of Area Sensitive to Desertification in Southern Italy, Proc.Of the 2nd Int.Conf. On New Trend in and Environmental Engineering for Safety and Life: Eco-compatible solutions for Aquatic Environmental, Capri, Italy. 6

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