Hydrological Investigations of Small Watersheds of Plateau Region of Bihar for Efficient Watershed Management
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Date
1996
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Birsa Agricultural University, Ranchi
Abstract
On account of undulating nature of terrain, light texture of upland soil with low organic matter content, unpredictable and erratic rainfall faulty cultivating practices and other biotic factors like uncontrolled grazing and destruction of forest the problem of soil erosion and water loss is the most alarming throughout the Plateau region of Bihar , Since the entire region cones under reinfed area, the improved natural resources development management and conservation to provide a reliable base for stable agricultural production are critically needed in the region. Under this situation watershed if the only natural focus of research where proper planning has to be made for soil and water management in relation to crop production system resource conservation and utilization.
The present investigation was therefore undertaken with objective to formulate the reliable response ,model s for predicting runoff water retention soil loss and nutrient loss along with evaluation of crop response for rainfed conditions under different cropping system identification of low investment high return crop combination and optimal allocation of land resources for different crops to get the maximum net return with minimum soil loss from small agricultural watershed of plateau region of Bihar.
For estimating and quantifying the runoff sediment loss and nutrient loss the experiment of runoff2 plot under controlled condition with Arhar and groundnut as cover crops was conducted. On the basis of the data generated from this experiment mathematical models for runoff water retention sediment loss and nutrient loss were developed. The experiment was also conducted on watershed basis under Arhar +groundnut ,Arhar + maize cropping system and the predicted values of runoff water retention, sediment loss and nutrient loss from mathematical models were compared with the observed values obtained from the watershed experiment to evaluate the validity of the models.In order to develop crop response under rainfed condition the effect of water retention on grain yield of different cropping systems.An experiment was also conducted to evaluate the most economical crop combination among different cropping system recommended for rainfed condition for the region All experiment conducted at soil conservation Reasearch station farm Demotanr Hazsaribagh. The optimal solution for land use pattern is evaluated for different activities with a view to maximum the net return and minimize the soil loss from Ranchi Swanrekha North potpoto Nala catchment in Kanke Block having 1820 ha of total agricultural land with consideration of meeting the food requirement of the population of the watershed area.
On the basis of analysis of twenty five years rainfall was found in the month rainfall was found in the month of July followed by August The rainfall predicted in the range of 40 to 60 per cent probability level may be applied for the estimate of runoff and soil loss and cultivation of suitable Khaarif crops under rainfed condition. The effective storm was found to be in the reabge of 60 to 65 per cent of the total rainfall. Maximum value of erosion index as 188.16 metric unit was found in the month of july expressing the higher rate of erosivity.
Mathematical model for prediction of per cent water retention was developed in terms of foliage cover and slope of the land .The runoff rediction model was developed by volume