The human habitations in the mountainous regions of India are dominantly dependant on springs for drinking water, domestic usage and agricultural needs. Springs are the lifeline of water supplies for these regions. They have been called different names in different parts of India; “Zhara” in Maharashtra or “Jhora” in West Bengal, “Dhara” in Sikkim or “Naula” or “Baori” in Himachal Pradesh and Uttarakhand, “Kuiphir” in Mizoram or “Ephut” in Manipur, “Chhimik” in Leh-Ladakh and Jharna in Odisha. Springs also form important cultural and religious symbols for humans, with many spring sites being places of worship and prayer. Springs play a vital role in providing ecosystem services in the form of base flows, which feed many small and large rivers, sustain some of the important wetlands and help balance the dry season stocks in many lakes. Springs are points on the Earth’s surface through which groundwater emerges and flows. Most springs are discharged from aquifers, a system of rocks/rock material, which stores and transmits water to such springs and to wells.
Natural factors like climate and seismic activity affect spring discharge. Anthropogenic factors like increasing demand due to rise in resident population and surge in tourist inflow is putting huge pressures on mountain aquifer systems. Ecological degradation associated with land use – land cover change, especially for infrastructure development are shrinking the natural recharge areas of the springs and leading to deterioration in spring-water quality. It is reported that half of the perennial springs have already dried up or have become seasonal, resulting in acute water shortage for drinking and other domestic purposes, across hundreds of Himalayan villages. A continuing crisis of spring water depletion will consequently affect lives of millions of people in the mountains – both resident and visitors.
A majority of water conservation programs in the mountains have revolved around the concept of watersheds and watershed development, in the past. Watersheds are best described as the units of the land surface that drain water from the ridgeline to a common point into the valley through a system of interconnected stream channels. The watershed concept only accounts for surface water movement. Springsheds differ from watersheds because the source of spring water is determined by aquifer characteristics and not surface topography. Also, movement of spring water, which is groundwater, is determined by the underlying geology, that is, nature of rocks, their inclination and structure. The point where the spring emerges is based on the relationship of the aquifer to the watershed surface. A springshed is a set of watersheds and aquifers that integrate into a system that supplies water to a group of springs.
Types of Springs
Springs are fed by aquifers, a system of rocks/rock material, which stores and transmits water to such springs. Different rocks show different properties that are characteristic of the process of the formation of the rock. The extent of mountains aquifers, their geometry and hydrological parameters exhibit large variation influencing spring behavior. Recharge to the spring is governed by spring type, aquifer geometry and its properties. Geologically, springs are classified into five types.
Depression springs are formed in unconfined aquifers when the topography intersects the water table, usually due to the surface stream incision. As the Springs are formed because of earth’s gravitational pull they are named depression or gravity springs. These are usually found along the hillside and cliffs.
Fracture springs occur due to existence of permeable fracture zones in low permeability rocks. Movement of groundwater is mainly through fractures that constitute the porosity and permeability of aquifers. Springs are formed where these fractures intersect the ground surface.
The term ‘Karst’ is derived from a Slavic word that means barren, stony ground. It is also the name of a region in Slovenia near the border with Italy that is well known for its sinkholes and springs. Geologists have adopted karst as the term for all such terrain. Cavities are formed in carbonates rocks (limestones, dolomites, etc.) due to dissolution of rock material by chemical reaction. Water moves through these cavities and openings to form a spring or a system of springs.
Faulting may also give rise to conditions in which groundwater (at depth) under hydrostatic pressure (such as in confined aquifers) can move up along such fault openings to form a spring.
Contact springs emerge at contacts where relatively permeable rocks overlie rocks of low permeability. Spring water emerges at such contacts.