Geospatial modeling for saline wetland ecosystem restoration

Rajashree Naik, Environmental Science, Central University of Rajasthan, Kishangarh, India and Laxmikant Sharma, Environmental Science, Central University of Rajasthan, Ajmer, India

Background/Question/Methods
Saline lakes occupy 44% and 23% of volume and area of all lakes around globe. These lakes might suffer from extended dryness, reduced hydroperiod, or complete desiccation by 2025 as seen in Aral Sea and Lake Urmia. These influenced billion-dollar global markets of salt, shrimp, and minerals besides environmental disruption. These triggered the curiosity about the Indian saline lakes, as India ranks third in global salt market exporting approximately 230 million tons to 198 countries. However, current study is conducted on Sambhar Lake, largest inland saline Ramsar site contributing 9.86% of total salt production. The lake is undergoing partial desiccation due to illegal saltpan encroachment stealing brine worth 300 million USD. The current study aimed to assess its trend of degradation, identify ecological indicators, and predict future status at landscape level. For this investigation, geospatial modelling was conducted for 96 years (1963-2059) at decadal scale with Cellular Automata-Markov model, ground data (birds-soil-water). Land Use Land Cover classification was conducted using CORONA aerial imagery of 1963 (before start of any satellite mission) and Landsat satellite imageries using supervised classification for 1972, 1981, 1992, 2009, 2019 and future prediction under Land Change Modeler of TerrSet platform for 2029, 2039, 2049 and 2059. Acquired images were classified into 8 classes as Aravalli hills, barren land, saline soil, salt crust, saltpans, waterbody, settlement, and vegetation integrated with bird-soil-water and field information.
Results/Conclusions
Past trend shows reduction of waterbody from 30.7 to 3.4% at constant rate (4.23%) to saline soil. Saline soil increased by 9.3% subsequently increasing barren land by 4.2%; saltpans by 6.6% and settlement by 1.2% till 2019. Future predictions show loss of 40% wetland and net increase in 30% vegetation, 40% settlement, 10% saltpan, 5% barren land, and net loss of 20%, each by Aravalli and salt crust by 2059. Saline soil conversion to barren land will be largest loss of 120%. Additionally, soil-water-birds census result state a loss of its saline character; subsequently reduction of migratory bird from 3 million to 3000. Saltpan-encroachment, groundwater extraction, hydrological structure construction, water diversion, and biological disruptions, have altered its water budget, hydrological communications, habitat, and productivity. In the light of UN Decade on Ecosystem Restoration (2021-2030), restoration strategies are suggested, if delayed, more restoration capital may be required than its revenue generation as happened in the case of Owen’s lake in California when US$ 3.6 billion was spent for its dust mitigation for 25 years.