Impact of Forestry Interventions on Groundwater Recharge and Sediment Control in the Ganga River Basin

Water related services of natural infrastructure will help to combat the risk of water crisis, and nature-based solutions involve the management of ecosystems to mimic or optimize the natural processes for the provision and regulation of water. Forested areas provide environmental stability and supply a high proportion of the world’s accessible freshwater for domestic, agricultural, industrial and ecological needs. The present work on “Forestry Interventions for Ganga” to rejuvenate the river is one of the steps toward the Ganga River rejuvenation programme in the country. The consequences of forestry interventions for Ganga will be determined on the basis of water quantity and water quality in the Ganga River. The study conservatively estimated the water savings and sedimentation reduction of the riverscape management in the Ganga basin using the Soil Conservation Service Curve Number (SCS-CN) & GEC, 2015 and Trimble, 1999 & CWC, 2019 methodologies, respectively. Forestry plantations and soil and moisture conservation measures devised in the programme to rejuvenate the Ganga River are expected to increase water recharge and decrease sedimentation load by 231.011 MCM·yr-1 and 1119.6 cubic m·yr-1 or 395.20 tons·yr-1, respectively, in delineated riverscape area of 83,946 km2 in Ganga basin due to these interventions. The role of trees and forests in improving hydrologic cycles, soil infiltration and ground water recharge in Ganga basin seems to be the reason for this change. Forest plantations and other bioengineering techniques can help to keep rivers perennial, increase precipitation, prevent soil erosion and mitigate floods, drought & climate change. The bioengineering techniques could be a feasible tool to enhance rivers’ self-purification as well as to make river perennial. The results will give momentum to the National Mission of Clean Ganga (NMCG) and its Namami Gange programme including other important rivers in the country and provide inputs in understanding the linkages among forest structure, function, and streamflow.

Riverscape Approach and Forestry Interventions for Ganga River Rejuvenation

Rivers have been degraded globally due to various reasons over centuries and limiting their ecological health and value, including Ganga River in India. Riverscape approach can provide relevant information on riverine resources needed in river restoration programmes. We propose a conceptual riverscape model to rejuvenate the holy river Ganga in India through forestry interventions after due consideration of ecological processes, mosaic of landforms, communities and environment within the large landscape of Ganga basin. The select riverscape area includes the area of 5 km and 2 km on either side of the river Ganga and important tributaries, respectively, all along the rivers in five stakeholder states of Uttarakhand, Uttar Pradesh, Bihar, Jharkhand, and West Bengal in the country. The width of the riverscape was taken from the maximum bank line in recent years on either side of river in the concerned state. However, all micro-watersheds in the hills of Uttarakhand state, being the origin place of river, have been included in riverscape area up to Haridwar. Here riverscape is a mosaic of different land uses viz., natural ecosystems, rural and agricultural ecosystems and built-up urban environment including flood plain and is an ecologically sustained system developed during the last 30 years due to river meandering all along the river. Geospatial modelling and GIS data on land use pattern, soil erosion rates, slope of the topography, etc. were used to classify riverscape area into high, medium and low priority areas to implement forestry interventions in delineated riverscape. Thereafter, forestry interventions were planned and carried out in three identified landscapes viz., Natural (forests), Agriculture (agroforestry), and Urban along with conservation activities. Forestry interventions in delineated riverscape are expected to increase water recharge and decrease the sedimentation load in the Ganga River and its tributaries.

Forestry Interventions and Groundwater Recharge, Sediment Control and Carbon Sequestration in the Krishna River Basin

It is a known fact that human activities have a significant impact on global rivers, making the task of rehabilitating them to their former natural state or a more semi-natural state quite challenging. The ongoing initiative called “Rejuvenation of Krishna River through Forestry Interventions” aims to contribute to the overall river rejuvenation program in the country. In this context, the effects of forestry interventions on the Krishna River will be evaluated based on water quantity, water quality, and the potential for carbon sequestration through plantation efforts. To assess the outcomes of this study, various methodologies such as Soil Conservation Service Curve Number (SCS-CN), Central Ground Water Board (CGWB) and Intergovernmental Panel on Climate Change (IPCC) have been utilized to estimate water savings, reduction in sedimentation, and carbon sequestration potential within the Krishna basin. The projected results indicate that the implementation of forestry plantations and soil and moisture conservation measures in the Krishna River rejuvenation program could lead to significant improvements. Specifically, the interventions are expected to enhance water recharge by 400.49 million cubic meters per year, reduce sedimentation load by 869.22 cubic meters per year, and increase carbon sequestration by 3.91 lakh metric tonnes per year or 14.34 lakh metric tonnes of CO2 equivalent. By incorporating forestry interventions into the Krishna riverscape, it is anticipated that the quality and quantity of water flowing through the river will be positively impacted. These interventions will enhance water infiltration, mitigate soil erosion, and contribute to an improved vegetation cover, thereby conserving biodiversity. Moreover, they offer additional intangible benefits such as addressing climate change concerns through enhanced carbon sequestration potential along the entire stretch of riverine areas.