Groundwater Cum Well Recharging Model

Though Kerala is receives high rainfall in the order of 3000mm per annum, the temporal variations in its occurrence leads to acute water scarcity during the non-monsoon periods. About 50% of the population in urban area and 80% in rural area are still depending on open wells for the domestic water needs in Kerala. In order to augment the natural supply of groundwater, artificial recharge of groundwater has become an important and frontal management strategy in the country.

The Thrissur District Administration in the year 2008 has launched ‘Mazhapolima’ project, an artificial groundwater recharge scheme to recharge the household dug wells directly by the rainwater harvested from the rooftops. About 8056 Mazhapolima units has been implemented till December 2012 in 58 Grama Panchayats with the active participation of Grama Panchayats, private agencies and beneficiaries. An attempt has been made to investigate the impact of this Mazhapolima project on groundwater system in Thrissur District. Two sample areas (watersheds/GP's) very close to each other (with and without Mazhapolima) representing three physiographic regions of the district has been selected for the study. Of which one sample area in each physiographic region without Mazhapolima project has been selected as control areas.

The analysis of the hydrogeological data generated from the study area indicates that direct well recharge by rainfall harvested from rooftops is augmenting the groundwater reservoir. The increase in utilizable groundwater potential with Mazhapolima is estimated for the sample area representing highland, midland and lowland is about 7.22, 14.08, and 43.35 Million litres respectively. The study also indicates that the impact of direct well recharge on groundwater regime in coastal and midland region is very significant, whereas in highland region it is marginal. It may be due to the relatively faster subsurface drainage in moderate to steep topographical characteristics of the highland region. About 347 respondents participated in the social survey. About 78% of the respondents were of the opinion that significant improvement is obtained in the groundwater availability in coastal and midland area. About 68% of the respondents were opined that in the highland area the improvement in groundwater availability is marginal. In highland area, more than 50% of the respondents are experiencing water scarcity during summer months.

About 68% of the respondents are of the opinion that proper maintenance of the system is highly essential for the better functioning of the system. Majority of the respondents (85%) has the opinion that there is a need for periodic maintenance of the recharge systems, usage of quality materials, and ensuring beneficiary participation in the implementation of well recharge system for deriving better results. Physico chemical analysis of water samples collected during post monsoon, monsoon and pre-monsoon seasons reveals that there is a slight decrease in pH in the well water samples collected from the recharged area. In the coastal region, it isImpact of Mazhapolima Project on the Groundwater Regime in Thrissur District Final ReportCentre for Water Resources Development and Management (CWRDM), Kozhikode-673571, Kerala.iiifound that the salinity level in water samples collected from recharged area is relatively low compared to the samples collected from the non-recharged area. High level of bacteriological contamination is detected in majority of the water samples collected from the study area. It may be due to the close proximity of leach pits/ septic tanks, etc. Lack of initial flushing may also lead to the bacterial contamination in recharged wells. Bacterial contamination in recharged wells can be controlled to a large extent by the installation of a filter system and initial flushing. Periodic disinfection (chlorination) can control the bacteriological contamination in well water to a large extent.

The study has revealed that direct well recharge by rainfall harvested from rooftops is augmenting the groundwater reservoir, and also improving the water quality. However, proper attention has to be given in selection of the area, quality of the material, installation of filters etc. Beneficiary participation has to be ensured in the implementation and the periodic maintenance for deriving better results and the sustainability of Mazhapolima project. About 70% of the households in the State are still depending on groundwater through open wells for meeting their domestic water demands. Hence, to enhance the water availability in household wells particularly during the summer months, the pilot project, Mazhapolima implemented in Thrissur District can be replicated to other districts also through the active involvement of beneficiary participation.