TR(BR)-2/2007 : Evaluation of water harvesting structures in the Kandi belt of Jammu region

Abstract

Kandi-belt is the steeply sloping submontane belt of the Himalayas fringing the Siwalik hills and extending discontinuously from Jammu and Kashmir to Assam. This dry-looking belt has undulating topography, steep and irregular slopes, erodible and low water retentive soils. Major land and water management problems being faced in the Kandi-belt include excessive runoff, soil erosion, land degradation and erratic water distribution in space and time hampering agricultural production. Population in the entire belt suffers from water scarcity. Groundwater table is deep and streams carry huge debris material during monsoon.

Ponds have played a crucial role in the Kandi-belt. Their water was utilized for domestic purposes and, to a limited extent, for irrigation purposes. These ponds also helped in improving the ground water regime in the region. Almost all villages in the Kandi-belt have one big pond to meet the domestic needs throughout the year. These big ponds were constructed with masonry work on three sides, the fourth side left open for the water to flow in. However, by the middle of the 20th century, piped drinking water supply led to the neglect of these ponds most of which are today in a state of utter neglect. A long-term solution to the water scarcity problem in the Kandi-belt lies in the rejuvenation of these village ponds.

In this study, an attempt has been made to evaluate the present status of ponds in terms of quantity and quality of the available resources. Field investigations have been carried out for 45 ponds in the Kandi-belt. In addition to the evaluation of physical features, water quality parameters, and soil properties, hydrological evaluation has been attempted and water balance analysis has been demonstrated for a sample large pond. For the estimation ofphysical features, the shape, perimeter, area, depth, storage volume, age, utility, and annual status of the ponds (whether perennial or seasonal) have been determined for all the surveyed ponds. Various water quality parameters that have been evaluated from the samples of different ponds include: pH, electrical conductivity, alkalinity, calcium and magnesium hardness, chloride, sulphate, sodium, potassium, nitrate and total dissolved solids (TDS). The physical parameters such as temperature, pH and electrical conductivity were determined. In general, the water quality of the ponds was not found suitable for domestic purposes.

At the periphery of 37 ponds, soil samples were collected for textural analysis. Soil texture in 17 ponds was found to belong to sandy-loam type and in other 18 ponds, it was found to be silt-loam type. Further, infiltration tests were carried out in the bed of three ponds using double-ring infiltrometer. Infiltration capacities of the bed of the ponds were found to vary from 1.2 mm/hr in silt loam to 5.4 mm/hr in sandy loam type of soil. For the hydrological evaluation, water balance studies have been carried out and demonstrated for a large pond so that different components of water balance (say inflow, evaporation losses, seepage

losses, outflow etc.) could be studied in detail. Because of the non-availability of any hydrological observations, inflow to a pond from its contributing catchment area was estimated by using the Soil Conservation Service (SCS) Curve Number method. A computer program was written to estimate the inflow to a pond using SCS method. Another computer program was written for the water balance computation of the pond at daily time step. The program reads daily rainfall, generated catchment flow, and evaporation depth and calculates the revised depth, area, storage, seepage and evaporation losses, and spill at daily time step.

Sohal pond was selected for water balance analysis. From the SCS analysis, the runoff coefficient for the catchment of Sohal pond was found to be 0.225. From the water balance analysis, it was observed that the pond remains perennial through out the year. Seepage loss is the major water loss factor for the pond. In the monsoon season, the spill from the pond is also appreciable. If the water of the pond is diverted for irrigation or other domestic use during such surplus periods, the storage of the pond can be optimally utilised. At present, the water of the pond is not used for any purpose. There is a strong need to conserve the quality and quantity of the water of Sohal pond which can benefit the society in the long run.

In this study, hydrological evaluation has been demonstrated for only one pond. However, generalized computer programs have been developed which can be used for the hydrological analysis of any other pond in the Kandi-belt. This study has the limitations of observation of hydrological data in the area. If only a simple staff gauge is installed in each pond and daily observations of pond water level are recorded, significant improvements in the analysis can be made and results can be verified. There is a strong need for the rejuvenation of ponds in the Kandi-belt for coping with the water scarcity problem. These ponds not only harness and preserve the surface water resources but also recharge the groundwater.