Reviving dying springs: A paper documenting the Sikkim experience of groundwater recharge using geo-hydrology

Introduction

The paper begins with a description of Sikkim. The sources of water in the Himalayas and the geology of the area are also described.

Literature review of spring related studies

Spring discharge as a function of the rainfall pattern, the recharge area characteristics and the nature of the aquifers that feed these springs. There is evidence of springs drying up either entirely or seasonally, which is attributed to several causes. Developing the spring catchment area has some effect in recharging springs.

Climate change as the new threat:

The Himalayas are experiencing rapid climate change. Studies indicate a trend towards warmer nights and cooler days, with increased rainfall except in winter which are becoming increasingly warmer and drier.

Objectives of the study

• to provide a better understanding of the basic characteristics of these springs by undertaking an extensive survey, 
• to use action research to explore whether these dying springs can be revived through a spring-shed development approach using geo-hydrology techniques.

Methodology

Description of the study area

Incidences of drought are mostly reported from the south central part of the state, which has the following vulnerabilities:

• located in the rain shadow
• uni-modal rainfall (June-September)
• steep slopes leading to increased runoff
• villages in upper catchments, decreasing rainwater harvesting potential

Collection of spring data

270 springs were first examined to note their basic characteristics, then the response to artificial recharge was studied for 5 springs. These springs were studied for their characteristics and hydro-geological mapping carried out. Spring-shed development was also carried out using these maps. The recharge measures implemented are detailed, as is the methodology of discharge measurement.

Rainfall data recording

Disaggregated rainfall data was obtained from the automatic weather stations installed by the ISRO.

Limitations

Spring data for the extensive study covering 270 springs was collected on a quarterly basis, Similarly, while rainfall was recorded within a 5km radius of the selected springs, the high variation of rainfall in the mountains leads to a lack of accuracy.The paper documents the results of spring-shed development after only one year, while the full impact of the artificial recharge work will be known only after 2–3 years.

Findings

Extensive study

The typology of the springs was found to be mostly depression and fracture with contact springs and Karst springs occurring only rarely. The springs also follow the rainfall patterns closely.

Intensive study

The 5 selected springs have depression and fracture typology. One of these was located in private land, while the other 4 were located in either community or forest land. Rainwater harvesting and groundwater recharge techniques were implemented using geo-hydrological knowledge. This showed promising results. 

Discussion

Water security for mountain peoples depends on the health of their springs. However, climate change impacts rainfall patterns which in its turn affects springs. Spring water is considered a public resource, but springs and their recharge zones are often in private fields. The techniques of increasing infiltration are widely known, however success depends on accurate identification of the recharge area. The watershed approach is not always reliable, especially in the Himalayan areas. Resource mapping on a  GIS platform and preparation of a village spring atlas has also been initiated.

Conclusions and policy implications

Solutions to the water crisis, especially in rural areas, hinges upon the storage of seasonal rainwater. An integrated approach that considers revival of hilltop lakes, streams and springs while developing their catchment is needed. Including the farmers in this process is crucial. The spring shed approach considers the underlying geology during planning, thus increasing accuracy.

While the authors' experience is that spring-shed development is easier in community and forest lands, they emphasise including farmers through providing horticulture and fodder development incentives. The authors also state that water supply programs are threatened by the drying up of springs. National water supply programmes may need to explore spring conservation. 

This study proves that artificial recharge augmentation in spring recharge areas is possible. The authors recommend, mainstreaming spring-shed development in programs related to watershed development, rural water supply, and climate change adaptation, especially in the Himalayan region. 

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