Kerala’s water budget, a step towards effective water management

Subject: Geography

Section: Physical geography

Context:

Kerala floods and water imbalance across the regions gave rise to the concept of “water budget” and “water conservation” in Kerala state. On April 17, 2023, Chief Minister Pinarayi Vijayan released the details of the first phase of the water budget.

Details:

The concepts of water budget and water conservation were floated by a few in 2018 and in 2019.
Kerala began recording the availability of water, its consumption, surplus and deficit in 94 gram panchayats of the state.

State of water availability in Kerala:

Unlike the northern states of India that get water from melting of snow, rainfall is the only source of water for Kerala.
The annual average rainfall in the state is around 3,000-3,200 mm from the two monsoon seasons and summer rains, but it exhibits significant variations depending on the geography.
The northern districts of Kerala receive very little rain after the south-west monsoon and hence require more long-term conservation methods than the southern districts which get both the returning monsoon and the summer rains.

Initiative taken:

Navakeralam Karma Padhathi (NKP) is an initiative to solve socio-economic challenges in the state.
Haritha Keralam Mission, which spearheads the water budget project, is a sub-mission under the NKP focusing on eco-friendy development initiatives in agriculture, water conservation and climate-resilient disaster management practices.

Water Budget:

A water budget is a hydrological tool used to quantify the flow of water in and out of a system.
In other words, it is an accounting of all water stored and exchanged on the land surface (rivers, lakes), subsurface (aquifer, groundwater), and atmosphere (precipitation, evaporation).
The concept behind a water budget is that the rate of change of water stored in an area is balanced by the quantity and rate at which water flows into and out of that area.
Hydrological engineers use this concept to form the basis of effective water-resource sustainability, management, and environmental planning.

The water budget can be expressed in several ways. The United States Geological Survey (USGS) defines the water budget for a small watershed as:

P + Qin = ET + ∆S + Qout

Where:

P = precipitation (rain, snow, etc.)

Qin = water flow into the watershed

ET = quantity of evapotranspiration from soils, surface water, plants, etc.

∆S = Change in water storage

Qout = sum of water flowing out of the watershed

Approach used in water budget:

While calculating availability, both surface water and ground water was taken into account in the water budget.
The scientific inputs for the calculation of the availability and requirement of water came from the scientific team at the Centre for Water Resources Development and Management (CWRDM).
The distribution of summer rain, south-west monsoon and north-east monsoon, variation in terrain, area under forest, landuse pattern, rainfall infiltration, groundwater recharge, water flowing into the panchayat and water made available outside the panchayat were all considered while calculating the supply and demand.
The consumption of water for domestic use, irrigation, business, tourism and industrial needs were factored in, while calculating the total demand.

Advantages of water budget:

The water budget is an excellent tool that will help the panchayats analyse water distribution, and bridge the gaps between demand and supply.
The water budget will aid gram panchayats to design interventions that will solve water shortages if any, plan their projects better, and also help to increase land under agriculture.