Inversion of inherent optical properties in optically complex waters using sentinel-3A/OLCI images: A case study using China\u27s three largest freshwater lakes

Inherent optical properties (IOPs) play an important role in underwater light field, and are difficult to estimate accurately using satellite data in optically complex waters. To study water quality in appropriate temporal and spatial scales, it is necessary to develop methods to obtain IOPs form space-based observation with quantified uncertainties. Field-measured IOP data (N = 405) were collected from 17 surveys between 2011 and 2017 in the three major largest freshwater lakes of China (Lake Chaohu, Lake Taihu, and Lake Hongze) in the lower reaches of the Yangtze River and Huai River (LYHR). Here we provide a case-study on how to use in-situ observation of IOPs to devise an improved algorithm for retrieval of IOPs. We then apply this algorithm to observation with Sentinel-3A OLCI (Ocean and Land Colour Instrument, corrected with our improved AC scheme), and use in-situ data to show that the algorithm performs better than the standard OLCI IOP product. We use the satellite derived products to study the spatial and seasonal distributions of IOPs and concentrations of optically active constituents in these three lakes, including chlorophyll-a (Chla) and suspended particulate matter (SPM), using all cloud-free OLCI images (115 scenes) over the lakes in the LYHR basin in 2017. Our study provides a strategy for using local and remote observations to obtain important water quality parameters necessary to manage resources such as reservoirs, lakes and coastal waters

Evaluating the outcomes of payments for ecosystem services programmes using a capital asset framework

There is a limited understanding of the conditions under which payments for ecosystem services (PES) programmes achieve improvements in ecosystem service (ES) flows, enhance natural resource sustainability or foster sustainable livelihoods. We used a capital asset framework to evaluate PES programmes in terms of their social, environmental, economic and institutional outcomes, focusing on efficiency, effectiveness and equity trade-offs. We found that PES schemes can provide positive conservation and development outcomes with respect to livelihoods, land-use change, household and community incomes, and governance. However, programmes differ with regards to contract agreements, payment modes, and compliance, and have diverse cross-sector institutional arrangements that remain primarily state-structured and external donor-financed. There is a consistent lack of focus on evaluating and fostering human, social and institutional capital. This reflects general inattention to how PES programmes consider the causal links between ES and outcomes. To enhance ES production and PES scheme accessibility and participation, we recommend strengthening the linkages between ES production and land-use practices, boosting private and voluntary sector involvement, encouraging property rights and tenure reform, improving financial viability, and adequately accounting for the distribution of programme costs and benefits among participants

Capturing secchi disk depth by using sentinel-2 msi imagery in Jiaozhou Bay, China from 2017 to 2021

Water clarity is a key parameter for assessing changes of aquatic environment. Coastal waters are complex and variable, remote sensing of water clarity for it is often limited by low spatial resolution. The Sentinel-2 Multi-Spectral Instrument (MSI) imagery with a resolution of up to 10 m are employed to solve the problem from 2017 to 2021. Distribution and characteristics of Secchi disk depth (SDD) in Jiaozhou Bay (JZB) are analyzed. Subtle changes in localized small areas are discovered, and main factors affecting the changes are explored. Among natural factors, precipitation and wind play dominant roles in variation in SDD. Human activities have a significant influence on transparency, among which fishery farming has the greatest impact. This is clearly evidenced by the significant improvement of SDD in JZB due to the sharp decrease in human activities caused by coronavirus disease 2019 (COVID-19)