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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:
Drought is one of the climatic, natural disasters, having an impact on both the economy and the society, with its long-standing problems. Drought by nature is a result of inter-related parameters. The study is based on the concept that the severity of the drought is a function of rainfall, hydrological and physical aspects of the landscape, leading to meteorological, hydrological and physical drought. To mitigate the drought, some of the drought proofing measures such as rain water harvesting structures, soil and moisture conservation measures, fodder fuel wood and forest development along with employment generation and social security programs were suggested.

INTRODUCTION
Drought is one the climatic as well as natural disasters common all over the world. Droughts have disastrous impact on the economy and can affect the largest segment of the society, which may last for months and in some cases several years. Drought is more often like a cancer on the land, mute but sure assaulter that seems to have no marked beginning or ending; a malaise slowly engulfing the community and often leaves just as gradually.

Drought may be categorized as continuing disasters and as the time passes, the situation may further deteriorate. The continuing disasters include prolonged droughts and crop failure. These continuing disasters or drought affects a very large area. The droughts may compound long-standing problems of deforestation, encroaching desertification, soil erosion, forced migration, malnutrition, epidemics and loss of life over vast stretches of land for many years. Agriculture may suffer severe set back and large groups of affected population may have to migrate. In turn, it may cause pressure on urban centers, creating new demands and infrastructure.

The meteorological causes of drought are usually associated with slow, prevailing, subsidizing motions of air masses from continental source regions. These descending are of order 600 or 900 ft/day resulting in compressional warming of the air and therefore reduction in the relative humidity, inhibiting the cloud formation.

OBJECTIVES

  • To prepare Meteorological, Hydrological, Physical drought maps
  • Delineation of drought prone areas by integrating Meteorological, Hydrological and Physical drought
  • Suggestion of action plan for drought management.

DESCRIPTION OF THE STUDY AREA

Location and Extent: The study area is in the SW part of the Karimnagar district covering 10 Mandals. It lies between 78 51 to 80 34 E longitude and 17 98 to 19 07 N latitude, covering an aerial extent of 2101.57 sq. km. The study area is surrounded by Medak and Warangal districts in the south, Nizamabad in the west and parts of Karimnagar in north and east.

Topography : The topography of the study area comprises of hills and plain areas. Manair River flows through the study area and joins Godavari River. Mula vagu, Nakka vagu, Pedda vagu etc are the other sub-streams flowing in the study area, which ultimately meets Manair River. All these streams and rivers remained dry due to insufficient rains. The study area has a prominent reservoir, "Manair Reservoir " and other water bodies (cheruvus).

Geology and Soil : The Geology of the study area comprises of granite as hills and inselbergs. The major soil types are Chalkas, Red sandy soil, Dubbas, Deep red to loamy soil and very deep black cotton soil.

Temperature and Climate : The maximum temperature of the study area is 41.3 C and the minimum temperature is 13.4 C. The climate of the area is hot and humid.

Rainfall : The average annual rainfall ranges from 900 - 1500 mm. Most of the rainfall is by South-west monsoon.

Agriculture : The major crops grown in Karimnagar district are Rice, Groundnut, Cotton, Oil seeds, Paddy, Sugarcane, Jowar, Castor, Maize, Sunflower, Turmeric, Pulses and Chillies.

Forestry : The study area has reserved forests, mostly confined to hilly areas. Various JFM programs are being undertaken in these reserved forests as a part of Community Forest Management. Sirsilla, Bhimgal, Konasamudram R.Fs, etc are the major reserved forest areas.

Economy : Sirsilla town of the study area is one of the industrial centers dealing with Handlooms. The other prominent industries of Karimnagar are Coal mines, Thermal power plant, etc.

Culture and Religion : The prominent religious places in Karimnagar are Vemulawada, Kaleshwaram and Dholikatha Buddhist remains etc. Sri Vemulawada Rajarajeshwari temple falls in the study area. Vemulawada Bheema Kavi hails from this place.

Population : The Population of entire Karimnagar district is 3,477,079 with Population density 294 persons / sq. km. The literacy of the district 56 % and 40.3 % people live below poverty line.

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.

Kriging : "An interpolation technique for obtaining statistically unbiased estimates of spatial variation of known points such as surface elevations or yield measurements utilizing a set of control points". The spatial variation is quantified by the semi-variogram. The sample semi-variogram is calculated from the sample data with the equation :

where n is the number of pairs of sample points separated by distance h.



Statistics of 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.



Statistics of Physical Drought.



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.

  1. Built-up land
  2. Agricultural land
  3. Fallow land
  4. Forest Area
  5. Dense Scrub
  6. Water logged areas
  7. Land with or without scrubs
  8. River Sand or Sandy area
  9. Stony waste/Sheet rock area
  10. Rivers / streams
  11. Lake / Reservoir/ canal


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
  • Check Dams
  • Percolation tanks
  • Diversion drains
  • Farm ponds

b) Soil and Moisture Conservation Measures
  • Vegetation Barriers, Contour Bunding
  • Broad Bed and Furrow Method of Cultivation
  • Irrigation Water Management

c) Fodder, Fuel wood and Forest Development
  • Fodder and Fuel wood
  • Social Forestry and Silvipasture
  • Afforestation

2. Employment Generation Programmes
  • Food For Work Programme (FFWP)
  • Employment Assurance Scheme (EAS) (Rs. 16.0 billion)
  • Jawahar Gram Samridhi Yojana (JGSY) (Rs. 16.5 billion)
  • Pradhan Mantri Gram Sadak Yojana (PMGSY) (Rs. 25.0 billion)
  • Swaranjayanti Gram Swarozgar Yojana (SGSY) (Rs. 5.0 billion)

3. Social Security Programmes
  • Antyodaya Anna Yojana (AAY)
  • National Old Age Programme (NOAP)
  • Annapurna Scheme (Rs. 3.0 billion)
  • Integrated Child Development Scheme (ICDS)
  • Mid Day Meal - School children

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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  2. Barrett E.C and Curtis L.F (1982) - "Introduction to Environmental Remote Sensing", 2nd edition (USA by Chapman and Hall).
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  4. Environmental Systems Research Institute (ESRI - 1989) - ARC/INFO - Training course material.
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