Conclusion

Riverine ecosystems are disturbed by human interference. The current study affirms that burgeoning anthropogenic activities resulted in the loss of contiguous interior forest cover, leading to forest fragmentation and the decline of ecologically sensitive habitats. The area under non-forest has increased to 49.34% (in 2018). Field investigations and subsequent data analyses reveal that factors such as the type of forest cover, monoculture plantation, and agriculture played a crucial role in sustaining the water in the ecosystem, evident from the flow regime. The sub-watersheds in Aghanashini with native vegetation had higher eco-hydrological indices (EHI). The eco-hydrological footprint assessment at the sub-watershed level reveals that native vegetation forests in the catchment sustain water. The relationship is evident from water availability during all 12 months in streams with a native vegetation cover of >60% in the catchment, compared to the seasonal streams in the catchment with a vegetation cover of <30%. The study highlights that streams are perennial in the catchment with a native forest cover of >60% and a higher number of endemic plant species, confirming the linkage between ecology and hydrology with land-use dynamics. The hydro-ecological investigation provides invaluable insights into the need for integrated approaches in river basin management in an era dominated by mismanagement of river catchments with the enhanced deforestation process, inappropriate cropping, and poor water use efficiency. The premium should be on conserving the remaining evergreen and semi-evergreen forests, which are vital for water security (perennial streams) and food security (sustenance of biodiversity).

Pearson’s correlation coefficient revealed a high correlation among ionic parameters. The WQI results represented in a single number enabled the assessment of overall water quality during the monsoon, post-monsoon, and pre-monsoon seasons. Multivariate statistical approaches applied to water quality data of streams in Chandikaholé’s sub-catchments of the Aghanashini River basin helped to understand pollution sources and site suitability. Streams were categorized as less polluted, moderately polluted, and highly polluted sites based on their similarities in the water quality variables after the cluster analysis. A principal component analysis revealed that EC, pH, DO, total alkalinity, total hardness, evergreen forest, and flow duration play a crucial role in streams. The current study provides insights into the role of forests with native species in sustaining the local demand by maintaining the hydrological regime and preserving water quality, which is helpful in the watershed (catchment or basin) management by the respective government agencies.

The research outcome helps in developing the appropriate mitigation measures to maintain river basins’ ecological and hydrological integrity to sustain water. In addition, it helps in communicating with the public and decision makers to implement prudent management of the catchment through participatory approaches involving all stakeholders.

The current study is based on monitoring a free-flowing river in the Western Ghats, with the hot moist sub-humid climate regime (with a catchment of 1449 km2), which has to be validated for the larger spatial extent river catchments covering diverse agroclimatic regime. The next phase of the research focuses on applying this protocol for the Krishna River catchment with the wider agroclimatic regime and across administrative regions.

Supplementary Materials: The following supporting information can be downloaded at: www.mdpi.com/xxx/s1, Figure S1: Method for eco-hydrological and environmental regime assessment; Table S1: Details of data with sources; Table S2: Category-wise land use (with accuracy assessment) and forest fragmentation extent (in percentage); Table S3: Sub-basin wise forests and eco-hydrological status; Table S4: Average values of physicochemical parameters at different sampling sites; Table S5: Correlation coefficient matrix of water quality parameters of streams; Table S6: Loadings of 17 variables extracted from PCA.

Author Contributions: R.T.V. designed the experiments, finalized field experiments, funding acquisition, writing of the manuscript, editing, and final review; V.S. collected experimental data of hydrologic regime, spatial data analyses, a draft of the part of the manuscript; A.K.S. and S.V. collected field data (water quality), field samples analyses, data analyses, writing a part of the manuscript; B.S. carried out land use and fragmentation analyses using remote sensing data, compiled flora and fauna details, and wrote those sections in the manuscript; B.H.A. completed the manuscript writing,and review. All authors have read and agreed to the published version of the manuscript.

Funding: This research was funded by (i) ENVIS Division, The Ministry of Environment, forests and climate change (MoEFCC), Government of India [SP/DEOO-20-001] and (iv) Indian Institute of Science [IISc R1011].

Institutional Review Board Statement: Not applicable.

Informed Consent Statement:

Research Ethics: The publication is based on the original research and has not been submitted elsewhere for publication or web hosting.

Animal Ethics: The research does not involve either humans, animals, or tissues.

Permission to Carry out Fieldwork: Our research is commissioned by the ENVIS Division, The Ministry of Environment, Forests and Climate Change (MoEFCC), Government of India, and hence no further permission is required as the field work was carried out in in the non-restricted areas.

Data Availability Statement: Not applicable.

Acknowledgments: We thank Sreekanth Naik and Vishnu D Mukri for their assistance during the field data collection. We thank all the stakeholders of the Aghanishini River basin for actively taking part in the scientific discussions and cooperation during field data compilation. We are grateful to the official languages section at IISc for the assistance in language editing.

Conflicts of Interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.