Drought Assessment and Mitigation through GIS and Remote Sensing N. Satyanarayana*, K. Sudha**,V. Anjaneyulu***, M. Rajendra Prasad****, K. Chakravarthi***** * System Designer (GIS), Centre For Good Governance, Hyderabad. ** Junior Research Fellow, Forest and Ecology Division, NRSA, Hyderabad. ***Forest Range Officer (GIS), AP Forest Department, Hyderabad. **** Senior GIS Engineer RMSI, Hyderabad. *****Project Scientist, AP Forest Department, Hyderabad.
ABSTRACT:
INTRODUCTION
OBJECTIVES
DESCRIPTION OF THE STUDY AREA
METHODOLOGY 
Preparation of Thematic layers:
Meteorological Drought Map:
Rainfall is a key environmental parameter in assessment of Meteorological drought which reaches the earth's surface in different forms. The monthly-wise rainfall data of various rain gauge stations for the last 15 years (1985 - 2000) was taken for the study (Source: A. P. Irrigation Department). The minimum and maximum mean average rainfall of the study area is 655mm and 1007 mm respectively. Kriging interpolation technique was performed for categorizing the meteorological drought.
Preparation of Physical or Agricultural Drought Map : Agricultural drought is brought about when there is insufficient moisture for average crop or range production. This condition can arise, even in times of average precipitation, due to soil conditions or agricultural techniques. Land use land cover, soil drainage and geomorphology themes were used as input themes for deriving the physical drought. Each input layers were assigned weightages based on the physical conditions. All the layers were integrated using overlay analysis to derive physical drought. The weightages were summed up and resclasified into 4 major classes. 
Land use and Land Cover Map : It is derived from IRS 1D LISS III multi spectral data by performing unsupervised classification technique with following classes.
Soil Map: The soil map of the study area shows the following soil characteristics such as soil composition, physiographic units and soil drainage condition of the study area(Source: NRSA) Soil Characteristics with Physiographic unit, Composition and Class. 
Geomorphology Map: The geomorphology map has the following geomorphic units with varying ground water potential  
Preparation of Hydrological Drought Map : Hydrological drought deals with surface and subsurface water supplies such as stream flow, reservoir/lake levels, ground water. Extended periods of lacking precipitation cause these water supplies to drop below normal. Hydrological drought map was prepared using surface water source, irrigated area,stream density in the sub watershed and ground water well level data as input themes or layers. For each input layers weightages were assigned based on the logical applications and were grouped or categorized into 4 classes.  Preparation of Stream Density Map : Stream Density or Drainage Density is a measure of the texture of the drainage basin. Stream Density is defined as the mean length of streams within a basin per unit area and is obtained by dividing the total stream length ( L) by the total basin area (Au).   Preparation of Drought Prone Areas Map : Drought analysis is the function of Meteorological, Hydrological and Physical drought . They are integrated in GIS environment to derive the final Drought prone area map. Statistics of Drought Prone Areas.  RESULTS AND DISCUSSION Drought Analysis : The result shows severe drought mainly in the southern region covering 369.10 sq.km of the total area i.e., 2101.57 sq.km which is approximately 17.56%. The severe drought class of Meteorological, Hydrological and Physical Droughts covers an area of 60.29 sq.km, 515.77 sq.km and 218.92 sq.km respectively. The high drought area extends around those of severe class covering an area of 849.31sq.km, which is 40.41%. The statistics of Meteorological drought shows that high drought class accounts 47.89% i.e., 1006.48 sq.km of the total area, with mean average rainfall varying between 731mm-810mm. The high drought class of Hydrological drought covers an area of 845.28sq.km i.e., 40.22%. the physical drought statistics shows high drought accounting 38.34% ie., covering 805.72 sq.km. The moderate and least drought areas are found extensively in the northern and eastern part of the study area, particularly along Manair river. The statistics shows Ellanthakunta ,Sirsilla and Yellareddy Peta mandals are greatly effected by the drought conditions. The high drought mandal in the study area is Yellareddy Peta covering and area of 166.56 sq.km and the severe drought mandal is Ellanthakunta with 96.18 sq.km area. Increasing land use patterns, insufficient rainfall conditions and excessively drained conditions of the soils in these mandals are some of the reasons for the drought. If the above conditions prevails, there is a possibility of these high drought areas, converted to severe drought areas and further leading to desertification. Hence Action plan for drought management in these mandals is essential to mitigate the drought. Action Plan for Drought Management To address drought situation effectively certain conservation measures are suggested considering the earlier research works like. 1. Drought Proofing Works a) Rain Water Harvesting Structures
b) Soil and Moisture Conservation Measures
c) Fodder, Fuel wood and Forest Development
2. Employment Generation Programmes
3. Social Security Programmes
CONCLUSIONS India being a tropical country with hot and humid climates and high temperature conditions. Delay in the monsoons as well as high evaporation rate of the surface water bodies is making some of the regions into drought areas. In particular Karimnagar district is one of the drought prone district with reports of economic and human loss. As the drought is dynamic in nature, which builds over a time, timely and reliable information is essential for effective drought monitoring and management. Satellite remote sensing provides multi-spectral, multi spatial and multi temporal data useful for drought monitoring, assessment and management. The present study is a comprehensive evaluation and integrated analysis of drought, which has been carried out by using satellite based Remote sensing and GIS techniques. The study area experiences semi - arid climatic conditions, with average annual rainfall of about 1100mm. The maximum and minimum temperatures are 41.3°C and 13.4 C respectively. The study was aimed at assessing the drought prone areas, based on the meteorological, hydrological and physical drought parameters. Rainfall data, stream density, ground water data, irrigation and water source area, land use and land cover data, soil and geomorphology data were used in assessing the various drought types as well as drought prone areas. The various drought prone areas were classified further into four different classes of drought. According to the results, severe drought class accounts 17.56% i.e., 369.10 sq.km of the total area and out of which 96.18 sq.km was covered in Ellanthakunta mandal alone. The drought statistics also shows high drought prone area accounting for the large area covering 849.31 sq.km i.e., 40.41 % of the total area. Adverse climatic conditions may further convert these high drought prone areas to severe drought areas. Some action plans comprising of drought proofing works, employment generation programmes and social security programs were discussed for managing the drought prone areas. The present study of drought assessment and mitigation is an integrated approach of Meteorological drought, Hydrological drought and Physical drought types. The study, though having some limitations, is an ideal approach for drought analysis, as the meteorological, hydrological and physical drought parameters are interrelated for any prevailing conditions of drought conditions. References
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