Mr. Pranadh will present his APS as per the detail below:
Date: 12th October 2022
Time: 0930 - 1030 hrs.
Venue: CTARA Conference Room No.1
Title: Evolution of lakes from rural to urban system and impacts on lake hydrology, ecosystem services and people- a case study of Bengaluru lakes
Supervisor: Prof. Pennan Chinnasamy
RPC Members: Prof. Parmeshwar D. Udmale, Prof. Haripriya Gundimeda
Abstract:
In India, water bodies such as lakes are under tremendous pressure due to the urban transformation of rural landscapes. On the same grounds, interconnected systems of lakes in Bengaluru also faced the consequence of unsustainable urbanisation affecting the water balance, provision of ecosystem services and dependent communities. At present, 98 % of the lakes have already encroached, 90% are sewage fed, and 82 % show a reduction in their catchment area, while the rejuvenation efforts failed to meet the desired outcomes. Failure of such steps is attributed to the conceptualisation of lakes as urban commons instead interconnected Socio-Hydro-Ecological(S-H-E) systems; hence failed to capture the larger interconnectivity, holistic nature, inherent asymmetry and expansion of stakes. So, there is an urgent need to revisit the processes in lake transformation from rural to urban settings to assess impacts and develop better management plans. However, observation data to support such analysis is limited.
Combining the fact that lakes are S-H-E systems and considering the capabilities of Remote Sensing and GIS (RS & GIS) tools, interdisciplinary approaches need to be considered for assessing the impacts of rural to urban transformation, solving environmental challenges and livelihood security. Land Use Land Cover Change (LULCC) analysis in association with hydrological modelling and ecosystem services assessment would help in quantifying impacts and assessing causative factors for better management scenarios. In this context, the gaps identified in the existing literature are; need for a proper unit of analysis (defined boundary), incorporation of externalities, and socio-economic impact assessment on the hydrological scale (on a lake series scale). Based on this, the major objective of this study is to understand the social, hydrological and ecological impacts of rural-to-urban transformation of lakes in Bengaluru.
The site selected for the study is Yele Mallappa Shetty Lake series situated in Hebbal valley considering four major factors i) a significant share of their area falling under the city boundary ii) the presence of an end lake on a lake chain (YMS lake) draining to river ii) fair distribution of urban, peri-urban, and rural areas and iv) limited research and publications comparing to other lake series. From the preliminary field visit, findings are analysed at two scales i) YMS lake series and ii) YMS lake. LULCC analysis between 1989-2020 in the YMS lake series finds that the built-up area, open spaces and aquatic vegetation have increased by 57.1 %, 28.7% and 237.4%, respectively. At the same time, the extent of water bodies and agriculture and tree cover is reduced by 40.7 % and 50.6%, respectively. A closer look on YMS lake shows the non-perennial to the perennial transformation of the waterbody (with wastewater) declined traditional uses (mostly consumptive uses), and a newer set of uses emerged utilising the ‘new resource’- wastewater. While studies in relation to water quality are common in the valley, the efforts to quantify the change in the water balance of the lake in the context of emerging(contested) economic opportunities (like water transfer) and ecological degradation are limited. Hence, the review proposes using the interdisciplinary watershed modelling tool Soil and Water Assessment Tool- SWAT to further analyse hydrological processes due to urbanisation based on the availability of data and satisfactory model performance in ungauged stations. Thus, it helps set a further direction for future work for assessing impacts on lake hydrology, ecosystem services and people, which can aid the development of scientifically validated management plans.