:: CSRE IIT,Bombay

Abstract: The main theme of the project is towards development of few components of decision supporting system (DSS) for drought management in a watershed.

The required information and technology for local administration and end-users are to be assessed first through field survey and discussion. Both causes and effects of drought will be assessed individually and integrated using meteorological, hydrological, geo-hydrological, Socio-economic and remote sensing data. The degree of assessed drought hazard will be mapped using the techniques of Geographic Information System (GIS). Using existing database the seasonal/annual drought forecasting/early warning system model will be developed. The type of forecasting model will be arrived at depending on the requirement of end-users after the statistical survey. Other land based management scenarios, viz., ground water potential zone; rainwater harvesting potential zone and cultural practices will also be reviewed. The available data network and required data network will be figured out at the end of the study.

The current research project has been considered as phase-I against a three-phased integrated drought management system over DPAP area.

Highlights/Findings: It is a sub humid zone. Summer season (March – May) is too hot. The weekly averaged ambient temperature and humidity ranges are 12-43oC and 15-100% respectively. The normal annual rainfall over the area is good but the normalized deviation of monthly rainfall extends frequently from –1(no rainfall conditions where normal rainfall exists) to +2(double of the normal rainfall) and above. End users experience the late onset as well as early withdrawal of monsoon, a major reason for crop failure. They frequently face the drought conditions even for their livelihood.

The area corresponds to eastern fringe of Chhotanagpur plateau and gradually merges with depositional fluvial terraces of Damodar-Dwarkeswar-Kangsaboti River. The terrain is mainly granite and gneiss with enclaves of metasedimentaries and metabasics.
The river system, Dwarkeswar as Beko Nala originated from upland of Purulia. Gandheswari is the principal tributary of Dwarkeswar and originated from northwestern upland of Bankura. The drainage of Dwarkeswar is mainly dendritic, parallel to sub-parallel in pattern (Figure1). There are few reservoirs for minor irrigation, viz., Majra, Indrabill and Jharsia. A large number of ponds, those are mainly under the owner of the land, were found over the area. The historical study says the geological parameters have significant control on ground water occurrence over the study area. The aquifer systems are three types: weather mantle, saprolitic zones and fractured zones of the country rocks. Draft demand is much higher than present recharge rate. The irrigation is required even in kharif season as the crop yield is sensitive to water scarcity.

Agricultural drought is predominated due to soil hazards. The cultivable land is mainly mono-cropped due to water scarcity during Rabi and summer season. No certain plan is yet declared to develop spatially distributed irrigation covering DPAP area. The land use/land cover is classified into five major categories: forestland, agricultural land, wasteland, water bodies and settlement. The forestland further can be classified into scrubland, land without scrub, natural forestland and planted forest land. Principal crop is rice. Wheat and maize are also under principal crops. Land capability is moderately good. The problem of soil and ground water storage is added complexity to fight against drought. Population density is not significantly high other than the township area.

Data Used:

Output: The major reasons for adverse situation over this watershed under Chhotonagpur plateau was observed due to Aberrant rainfall, high heat effect, geomorphic stress & soil stress. The predictability of favourable weather is dominated by uncertainty factors. The end-users frequently face the drought conditions even for their livelihood. The irrigation is required even in kharif season as the crop yield is sensitive to water scarcity. Preliminary assessment on available information found the relationship between rain and crop. There is a good correlation between cultivated land and annual rainfall. More detail data analysis is in progress to establish the relationship. The correlation is most significant with the rainfall in July month and cultivated land (Figure2). In general 15% of total cultivable land of DPAP blocks is under irrigation in DPAP area of Bankura district (Table1). The scenario of irrigation is monitored through field survey, which is relatively better in Purulia where rate of water draining is more. People prefer jore-bundh, a minor irrigation system (Figure3, Figure4). Ground water storage in general is insufficient, as most of the dugwells and wells are dry in summer even in winter season. Draft demand is much higher than present recharge rate. A land use study and field survey noticed that a significant part of wasteland may be cultivable waste land. Other part of wasteland consists Rocky/stony waste and land without scrub. Soil depth is mostly moderate (22.5cm - 45cm) in the study area. Severely eroded steep upland with exposed rocks is having shallow soil depth (<7.5cm). Soil depth is deep (45cm-90cm) in light textured soil. In valley bottom soil depth is very deep (90cm-150cm). Land slope is mostly southeasterly.
A significant gap in ground level documentation is found to implement DSS especially for drought hazard.
(Note: The study is in progress)

Date of project completion: June, 2005

Total Cost of Project: Rs.15, 66,000/-

Project Investigator:

Dr. RINA JANA,
RESEARCH SCIENTIST
C.S.R.E., I.I.T. BOMBAY,
POWAI, MUMBAI 400 076.
TEL: (022) 2576 7679,
FAX: (022) 2572 3190
E-MAIL: rina[at]csre[dot]iitb[dot]ac[dot]in

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