Pamba River Research Articles

Introducing a climate, demographics, and infrastructure multi-module workflow for projected flood risk mapping in the greater Pamba River Basin, Kerala, India

Enhanced understanding of extreme events is essential for comprehensive risk assessment promoting informed decision-making and early warning to ensure the resilience against challenges imposed by changing climate. This study proposes a novel multi-module integration framework for the comprehensive evaluation of future flood risk in the Greater Pamba River basin, Kerala, India. The integrative modelling framework is developed by assembling a Cellular Automata-Markov Chain (CAMC) based and Use/Land Cover (LULC) projections, Reliability Ensemble Averaging (REA) of Global Climate Model (GCM) rainfall projections, Bayesian approach-based population projection, and spatial analysis of projected infrastructure and Digital Elevation Models (DEMs). By seamlessly interweaving the associated datasets, we illustrate the intricacies of flood vulnerability, exposure, and frequency across multiple return periods (2, 5, 10, and 100, 200 and 500 year) leading to the creation of diagnostic and prognostic high-resolution flood risk maps. The resultant flood analytics and analyses shown that around 36 % of the villages/municipalities and between 70 and 80 % of the critical facilities like schools, hospitals, and flood relief camps are falling under high-risk zones, for the 100-year return period flood. This finding is in line with Kerala's devastating flood episode in 2018, which exhibited characteristics of a nearly 100-year return period flood. In light of a changing climate, population growth, and shifting landscapes, these approaches provide a roadmap for more informed decision-making and adaptive flood risk management measures.

Developing Non-Stationary Frequency Relationships for Greater Pamba River basin, Kerala India incorporating dominant climatic precursors

Abstract. Global climate changes significantly contribute to increased frequency of hydrologic extremes. This significantly underestimates the hydrologic design parameters, bringing of hydro systems to increased failure risk. In order to address this concern, the current practice of development of hydrologic frequency tools need to be updated accounting for non-stationarity. This study first considered a diverse set of statistical tests to examine the trend, change points, non-stationarity and randomness of streamflow, rainfall and temperature time series of scales ranging from daily to annual. The annual maxima time series indicated non stationarity against the stationary behaviour of daily series of hydro-meteorological datasets of the basin. Subsequently, this study developed the Temperature Duration Frequency (TDF), Rainfall Intensity Duration Frequency (IDF) and Flood Frequency (FF) curves of Greater Pamba river basin in Kerala India, the part of which was most severely affected by the near century return period flood event of 2018. The analysis was performed for a multitude of combinations of variations in distribution parameters with time and climatic drivers as physical covariates in the extreme value formulations. The study proposed a novel wavelet coherence (WC) based driver selection of most dominant combination of climatic precursors in developing FF and IDF relations of three locations of Kalloopara, Malakkara and Thumpamon and TDF curve of Kuttanad region in the basin, considering data of 1985–2015 period. The proposed WC framework considers bi-multi-and partial effects of climatic oscillations (COs) like El Niño Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO) in identifying potential drivers. The different WC formulations captured in-phase relationships of streamflows and rainfall with COs at intra-annual, annual and inter annual scales up to 4 years. The methods showed that addition of climatic precursors improved the NS estimates of flood and rainfall quantiles by more accurately capturing the magnitudes of extreme streamflows and rainfalls of 2018, 2021 than the time covariate formulations. However, the role of COs on extreme temperature is not found to be influential in developing TDF relationships, which needs further investigation.

Aquatic Insects as Bioindicators of Water Quality in the Achenkovil River, Kerala, India.

The origin of the Achenkovil River, the Devarmalai of Western Ghats, is within the Konni reserve forest of Pathanamthitta district, flowing through Pathanamthitta, Kollam, and merging with the Pamba river in the Alappuzha district. This study included the spatial variation of aquatic insect fauna with respect to water quality. The bottom water samples and insect fauna were collected bimonthly using a Niskin sampler and D-frame nets for a period of one year (February 2019 to January 2020). The study yielded 10736 insect fauna under 8 orders, 21 families, 35 genera, and 36 species. How the quality of the water affects biodiversity of aquatic insects was examined using multivariate statistical techniques (PCA and CCA) and Pearson's correlation coefficient. The findings showed that the upstream portion of the river has a remarkable diversity and quantity of aquatic insect species. The major insect group in the collected sample was ephemeroptera. There were no pollution-sensitive taxa in the middle stream or downstream portions of the river, which suggests that the water quality was declining. The middle stream and downstream sections of the river did not contain any pollution-sensitive taxa, indicating deteriorating water quality. Human-caused factors like washing, cleaning cars, and washing cattle and disposal of garbage are common in these regions. Because most aquatic insects are sensitive to environmental fluctuations, they can be used as an efficient tool in biomonitoring studies.

Real Time Water Quality Monitoring of River Pamba (India) using Internet of Things

— All of Earth’s living things depend on food and clean water to survive. River water monitoring is essential for gathering the data required to manage water quality in the present as well as the future. In this research, the water quality of the Pamba River is monitored and analyzed using the Internet of Things (IoT) during the monsoon and summer seasons. The Pamba River is the third-longest river in the Indian state of Kerala and one of the primary sources of drinking water in Kerala’s Pathanamthitta and Alappuzha districts. In conventional systems, the monitoring procedure entails manually collecting water samples from various places, followed by testing and analysis in a lab. This is costly and time-consuming. With developments in sensors, communication, and the Internet of Things (IoT), monitoring water contamination has become more and more crucial in recent years and provides accurate data. The system collects information from IoT sensors to evaluate the quality of the water, including pH, dissolved oxygen, temperature changes, and other parameters. The relevant officials are alerted in the case of any variation, and all of this data is stored in the cloud. The system also ensures real-time water quality monitoring.

Climate-Resilient Crops for a Sustainable Future: The Promising Case of Minor Millets in Tamil Nadu Irrigated Modernization Project (TNIAMP)

This study integrated continuous data on the impact of the area and yield of minor millets in the sub-basins of Tamil Nadu and correlated it with the area and yield of minor millets in the sub-basins cultivated under the TNIAMProject. In this study, minor millet crops such as foxtail millet, ragi, finger millet, and varagu were introduced in fourteen sub-basins and their yield was carefully collected. This included all parts of Tamil Nadu. This study investigated the suitability of different sub-basins for crop diversification by exploring matching management practices with respective yield potentials. In this study, it was recorded that the yield was more than 3000 kg per acre in the sub-basins of Nagarai River, Lower Vellaru, Pambar River, Krishnagiri, Lower Bhavani, Varaha River, Cauvery River, and Lower Tamirabarani. This has also increased the area under cultivation in these sub-basins. The study found that the area and yield of minor millets in the sub-basins of Tamil Nadu have increased significantly under the TNIAMProject. This is attributed to the input subsidy and technological interventions provided under the project. The study recommends that the excess yield of minor millets caused by the TNIAMProject should be converted into value-added products and documented for sale in the respective areas. This will help to increase the income of farmers and promote the cultivation of minor millets.

Basin-Scale Streamflow Projections for Greater Pamba River Basin, India Integrating GCM Ensemble Modelling and Flow Accumulation-Weighted LULC Overlay in Deep Learning Environment

Accurate prediction of future streamflow in flood-prone regions is crucial for effective flood management and disaster mitigation. This study presents an innovative approach for streamflow projections in deep learning (DL) environment by integrating the quantitative Land-Use Land-Cover (LULC) overlaid with flow accumulation values and the various Global Climate Model (GCM) simulated data. Firstly, the Long Short Term Memory (LSTM) model was developed for the streamflow prediction of Greater Pamba River Basin (GPRB) in Kerala, India for 1985 to 2015 period, considering the climatic inputs. Then, the flow accumulation-weighted LULC integration was considered in modelling, which substantially improves the accuracy of streamflow predictions including the extremes of all the three stations, as the model accounts for the geographical variety of land cover types towards the streamflow at the sub-basin outlets. Subsequently, Reliability Ensemble Averaging (REA) technique was used to create an ensemble of three candidate GCM products to illustrate the spectrum of uncertainty associated with climate projections. Future LULC changes are accounted in regional scale based on the sub-basin approach by means of Cellular-Automata Markov Model and used for integrating with the climatic indices. The basin-scale streamflow projection is done under three climate scenarios of SSP126, SSP245 and SSP585 respectively for lowest, moderate and highest emission conditions. This work is a novel approach of integrating quantified LULC with flow accumulation and other climatic inputs in a DL environment against the conventional techniques of hydrological modelling. The DL model can adapt and account for shifting hydrological responses induced by changes in climatic and LULC inputs. The integration of flow accumulation with changes in LULC was successful in capturing the flow dynamics in long-term. It also identifies regions that are more likely to experience increased flooding in the near future under changing climate scenarios and supports decision-making for sustainable water management of the Greater Pamba Basin which was the worst affected region in Kerala during the mega floods of 2018.

Aquatic Floral Abundance on Ichthyofaunal Community in a Forested Stream of Pamba River in the Western Ghats

Aquatic macrophytes are essential to the fish community because they offer food, protection from predators and shelter. The present study deals with the influence of the distribution and abundance of aquatic macrophytes on stream fishes. Twenty-one species of aquatic plants and 13 associated fish species were identified during the study period of January-December 2019. In the study stream, the abundance of aquatic flora positively impacted the fish community. Certain aquatic macrophytes were highly preferred by individual fish species in the area. The Podostemonads formed a major plant group along the stream. Emergent plants, especially Lagenandra toxicaria played an important role in maintaining the composition of the fish community. Hypselobarbus kurali is a known genus of food fish, and they exhibited affinity to the area covered with Lagenandra toxicaria. Hydrilla verticillata, the submerzed plant showed extensive growth during monsoon and supported a large number of Haludaria fasciata.

Unveiling Fish Community Response to Anthropogenic Stressors in Tributary Streams of Pamba River in the Western Ghats

The anthropic impact on stream environments is increasing uncontrollably and affecting rich biodiversity. The intensity of anthropogenic stressors and their influence on the fish community was studied from the tributary streams of the Pamba river in the Western Ghats from January to December 2019. We quantified the anthropogenic stressors using a metric scale, which combines the severity and proximity of the stressor to the stream environment. Agricultural practices, riparian cover removal, hydrologic modifications, tourism, and pilgrimage were recorded as major stressors in the investigated streams. In this study, human pressure significantly affected the ichthyofaunal community in the streams. Generalists were found to be more tolerant of environmental stress in their respective sites, whereas specialists were adversely affected. The stream with a high intensity of stressors supported greater ichthyofaunal diversity, especially those of generalist fishes. Streams with an intermediate level of disturbances were noted to support high species richness. In the Western Ghats streams in Kerala, the ichthyofaunal response to human pressure is not well documented. This study is the first of its kind to concentrate on how ichthyofauna reacts to stressors caused by humans. The variety of stream fish assemblages in the Western Ghats must be preserved, which calls for regular monitoring of stressors.

Study of Self Depuration Capability of River Pamba

The natural waterbody such as rivers and lakes are able to do the purification process themselves, which has the primary dependant of absorption capacity and dissolution capacity of atmospheric oxygen from the surface of the water body. The various pollutants such as biological pollutants and chemical pollutants are broken-down into insignificant strength over a period of time by the growth of certain bacteria. This bacterial growth in the water is possible only with the absorbed and dissolved oxygen content in the water. This absorbed and dissolved oxygen content in the water bodies are based on the velocity of the stream, depth, discharge rate and temperature of the water, thus the self-depuration capacity of the water bodies are depended on the natural profiles and environmental factors of the waterbody and its location. This explains that the turbulent water will get purified by itself in much higher rate than the stagnant water, which tends to become septic because of the oxygen scarcity. The degree of self-depuration of a natural water body is based on the physiochemical and biological activities occurring in the system. Various parameters like basic physical properties, chemical properties such as pH, hardness, dissolved solids, mineral content, BOD, dissolved oxygen for the samples were taken along the Pamba River. The samples are taken from three zones of the Rivers viz. 1) Forest zone, 2) Residential zone and 3) Industrial zone. The water quality factors from the samples are validated against the desirable values as per IS 10500: 2012 and justifies the current status of the River and recommendations for its wellbeing.

One dimensional hydrodynamic modelling of pamba river for identifying the flood vulnerability

Hydrodynamic modelling is a powerful tool to understand and analyse a river flow and its conditions. The identification of flood vulnerability areas of Pamba river helps to minimize the damages associated with the flood. A hydrodynamic river model was customised and calibrated for the river Pamba in Kerala using MIKE HYDRO River model. The model was calibrated using Manning’s roughness coefficient. In this study, we utilize the time series of daily discharge and water level of different gauging station of Centre Water Commission at Kallooppara, Malakkara, Thumpamon and water level data of Thottappalli spillway. The SRTM DEM was used to generate the flood model for the period June to August 2010. The model performance was assessed by comparing observed and stimulated water level at the upstream and downstream of the river. The correlation coefficient value obtained in the range of 0.53 to 0.94. The outcomes of the study can benefit future modelling effort through the provision of robust tool to predict water levels at various points of the river. This study can help the water resources policy makers for arriving at suitable mitigation measures.

Flood Modelling of Pamba River Using MIKE FLOOD

Flood hazard mapping and flood risk zoning are very effective in the monitoring and risk management of floods. For this flood inundation maps are required. Different computational models are available, such as one-dimensional (1D), two-dimensional (2D) and 1D-2D-coupled model. In this study a coupled 1D-2D hydrodynamic model, MIKE FLOOD was used to simulate flood inundation extent, water levels at different location of the river. MIKE FLOOD is a platform that combines the MIKE 11 and MIKE 21 models into a single modeling framework that is dynamically coupled. Using a coupled approach makes it possible to use the best features of all two versions of software. The study area considered is Pamba river in Kerala which is most effected region in 2018 flood. So flood modelling of Pamba river is necessary. The time series of daily discharge and water level of different gauging station of Centre Water Commission at Kallooppara, Malakkara, Thumpamon and water level data of Thottappalli spillway are used for the study. The SRTM DEM was used to generate the flood model for the period June to August 2010. At the downstream of the river, the maximum water level obtained is 1.48 m in 1D model and water depth obtained is in the range of 0.6 to 1.2 in 2D modelling. The correlation coefficient values ranges 0.52 to 0.96. This study will assist policy makers in the field of water management to achieve effective mitigation step

Preparation of Inundation Maps by Developing Unsteady Flow Model of Pamba River- Decision Support System for Disaster Management

Nowadays extreme rainfall events are more frequent across our country. Controlled releases from reservoirs would be necessitated to ensure the safety of dams and people downstream during extreme inflow. Mitigation measures are to be planned and preparedness actions to be taken effectively to reduce the impact of such catastrophe at downstream flood plains of reservoirs. Advance information on the extent of the area likely to be in undated consequent to releases from reservoirs is vital in developing an effective action plan for the timely evacuation of people. In the present study, it has been attempted to develop an unsteady flow model of the Pamba River in Kerala& the flood plain downstream for determining the area likely to be inundated corresponding to a largely controlled release in the tune of 900m3/s. The unsteady flow model is developed in HEC-RAS to study the flow behavior of flood wave caused by the flow hydrograph with peak 900m3/s as it propagates to the downstream plains. From the studies, it is found that the transformation of flow profile of flood wave can be better estimated using the HEC-RAS 2D flow model and the results can be used as important information in the decision-making process for Disaster Management Authorities.

Effect of great flood 2018 on the soil micro and meso fauna of Ranni Taluk adjoining Pamba river- Kerala

Effect of great flood 2018 on the soil micro and meso fauna of Ranni Taluk adjoining Pamba river- Kerala

Numerical Modelling of Flood Inundation and Run-Up along the Banks of Pamba River, South West Coast of India

The state of Kerala was in the shadow zone of several natural disasters. But the disasters which happened during the last two decades changed our perceptions and preconceived notions. Before two decades, for Keralites the term disaster was a matter of strange science fiction books, Hollywood cinemas or the things which were happening on the other side of the globe or planet. The tsunami of December 26, 2004, Ockhi of 2017, Kerala Floods of 2018 and its replicated version in 2019 exposed our vulnerabilities. During the event of 2018 Kerala Floods, the need for a Flood Warning System (FWS) in Kerala was badly felt. Though there are many components for a FWS, the main component of a FWS is the prediction of inundation and run-up along the banks of rivers/ water bodies. This component can only be accomplished through the process of numerical modelling. Numerical modelling is an efficient tool for estimating the past events and predicting the future ones. Through numerical modelling different scenarios of possible flood generating permutations and combinations will be carried out and hence in the event of a real time flood warning a closest matching will be picked from these, which will be subsequently used for mitigation. The results of numerical modelling will be the base for creating vulnerability maps which will be used for mitigation and rehabilitation. This investigation numerically simulates the possible flood rising inundation and run-up along the banks of Pamba River situated on the south west coast of India. The model results suggest that extreme rain fall events alone cannot inundate the banks of Pamba River, whereas external discharges emanating from dams, tidal reflections from the oceans etc. could inundate the terrain. The investigation also recommends several components for successfully establishing a flood warning system in Kerala with specific reference to Kerala floods 2018. How to cite this article: Praveen SS, Babu VS, Vijayan A, Babu SS. Numerical Modelling of Flood Inundation and Run-Up along the Banks of Pamba River, South West Coast of India. J Adv Res Alt Energ Env Eco 2020; 7(1): 8-14. DOI: https://doi.org/10.24321/2455.3093.202002

An assessment of water yield ecosystem services in Periyar Tiger Reserve, Southern Western Ghats of India

ABSTRACT Protected area water yield calculation and mapping are of great importance to the conservation planning and resource management. A water yield model based on InVEST was employed to estimate water yield in Periyar Tiger Reserve, a representative in the Southern Western Ghats, Kerala, India. The analysis included land use/land cover, average annual precipitation and potential evapotranspiration, soil depth at various elevation, and plants available water content. The estimated water yield of PTR was 2.33E+09 m3 y-1 with 67% from Periyar river watershed and 33% from Pamba river watershed. A comparison of water-yielding capacity to the forest ecosystems with different vegetations indicates that there is a decreasing trend from evergreen forest, semi-evergreen forest, to grassland-savanna, moist deciduous forest and plantations. It is estimated 37% of evergreen and 24% of semi-evergreen share the major portion of the total water yield, 63.5% of PTR. This study reveals the significance of ecosystem services of the protected area and the importance to conserve and required efficient management.

FIMAR: A new Fluoride Index to mitigate geogenic contamination by Managed Aquifer Recharge

The objective of this study is to develop a Fluoride Index for mitigation of geogenic contamination by Managed Aquifer Recharge (FIMAR). This index was tested by applying to the Pambar river basin in southern India. About 40% of the study area had fluoride >1.5 mg/L, contributed from the dissolution of fluorite, fluorapatite, biotite and hornblende. The relationship between groundwater level and fluoride concentration exhibited two types of relationship. In shallow wells, groundwater recharge during monsoon increases the groundwater level and dilutes the fluoride concentration. During summer, evaporation decreases the groundwater levels and increases the fluoride content. In deep wells, the fluoride-rich salts that is deposited in the unsaturated zone due to evaporation in the pre-monsoon season is flushed during groundwater recharge and thus, the fluoride concentration increases with increase in groundwater level. This relationship was used as a key layer in FIMAR. Overlay analysis including the well type derived from the groundwater level and fluoride fluctuation, average fluoride concentration, geology, geomorphology, soil, drainage density, land use, lineament density and thickness of the weathered zone indicated 30% of the area was suitable for MAR to mitigate fluoride contamination. Since the construction of new MAR structures is cost-intensive, it is proposed to rejuvenate the existing ponds in the areas identified by FIMAR to induce recharge and dilute fluoride concentration. The positive impact was confirmed using numerical and geochemical modelling. This proves that FIMAR can be used as a planning tool in fluoride endemic areas and that the future MAR methods will be beneficial to mitigate geogenic fluoride contamination.

Estimation of soil erosion in a rain shadow river basin in the southern Western Ghats, India using RUSLE and transport limited sediment delivery function

Soil erosion and deposition in a tropical mountainous river basin, viz., Pambar River Basin (PRB), in a rain shadow region of the southern Western Ghats (India) were modelled using Revised Universal Soil Loss Equation (RUSLE) and transport limited sediment delivery (TLSD) function in GIS. Mean gross soil erosion in the basin is 11.70 t ha−1 yr−1, and is comparable with the results of previous soil erosion studies from the region. However, mean net soil erosion from the basin is 2.92 t ha−1 yr−1 only, which is roughly 25% of the gross soil erosion. Although natural vegetation belts show relatively higher gross- and net-soil erosion rates (mainly due to high LS and C factors), their sediment transport efficiency is remarkably less, compared to the land use/ land cover types with anthropogenic signatures (i.e., plantations and croplands). Despite the lesser amount of annual rainfall, the high rates of soil loss from the semi-arid areas of the basin might be the result of the poor protective vegetation cover as well as isolated high intensity rainfall events. The study highlights the significance of climate-specific plans for soil erosion management and conservation of the soil resources of the basins developed in rain shadow regions.

Stable isotope characteristics of precipitation of Pamba River basin, Kerala, India

Stable isotope composition of precipitation from Pamba River basin, Kerala, India, is evaluated to understand the role of spatial and temporal variations on rainwater isotope characteristics. Physiographically different locations in the basin showed strong spatial and temporal variations. δ 18O varied from −7.63 to −1.75 ‰ in the lowlands; from −9.32 to −1.94 ‰ in the midlands and from −11.6 to −4.00 ‰ in the highlands. Local Meteoric Water Lines (LMWL) for the three regions were determined separately and an overall LMWL for the whole of the basin was found to be δ 2H = 6.6 (±0.4) δ 18 O+10.4 (±2.0). Altitude effect was evident for the basin (0.1 ‰ for δ 18O and 0.8 ‰ for δ 2H per 100 m elevation), while the amount effect was weak. The precipitation formed from the marine moisture supplied at a steady rate, without much isotopic evolution in this period may have masked the possible depletion of heavier isotopes with increasing rainfall. Consistently high d-excess values showed the influence of recycled vapour, despite the prevailing high relative humidity. The oceanic and continental vapour source origins for the south-west and north-east monsoons were clearly noted in the precipitation in the basin. Rayleigh distillation model showed about 30% rainout of the monsoon vapour mass in the basin.

Fluoride in weathered rock aquifers of southern India: Managed Aquifer Recharge for mitigation.

Climatic condition, geology, and geochemical processes in an area play a major role on groundwater quality. Impact of these on the fluoride content of groundwater was studied in three regions-part of Nalgonda district in Telangana, Pambar River basin, and Vaniyar River basin in Tamil Nadu, southern India, which experience semi-arid climate and are predominantly made of Precambrian rocks. High concentration of fluoride in groundwater above 4mg/l was recorded. Human exposure dose for fluoride through groundwater was higher in Nalgonda than the other areas. With evaporation and rainfall being one of the major contributors for high fluoride apart from the weathering of fluoriderich minerals from rocks, the effect of increase in groundwater level on fluoride concentration was studied. This study reveals that groundwater in shallow environment of all three regions shows dilution effect due to rainfall recharge. Suitable managed aquifer recharge (MAR) methods can be adopted to dilute the fluoriderich groundwater in such regions which is explained with two case studies. However, in deep groundwater, increase in fluoride concentration with increase in groundwater level due to leaching of fluoriderich salts from the unsaturated zone was observed. Occurrence of fluoride above 1.5mg/l was more in areas with deeper groundwater environment. Hence, practicing MAR in these regions will increase the fluoride content in groundwater and so physical or chemical treatment has to be adopted. This study brought out the fact that MAR cannot be practiced in all regions for dilution of ions in groundwater and that it is essential to analyze the fluctuation in groundwater level and the fluoride content before suggesting it as a suitable solution. Also, this study emphasizes that long-term monitoring of these factors is an important criterion for choosing the recharge areas.

Impact of human interventions on nutrient biogeochemistry in the Pamba River, Kerala, India

Anthropogenic inputs nowadays are the major source of nutrients to the coastal area. While a wealth of data exists from high latitude regions, little is known on the amount and composition of nutrient fluxes from densely populated tropical catchments. The South Indian Pamba River is a prime example in this respect because of its manifold human interventions such as the Sabarimala pilgrimage, the largest pilgrim centre in the world and agricultural practices. In order (i) to identify direct cause-effect relationships, (ii) to quantify land use specific nutrient inputs and (iii) to assess the respective impacts water was sampled along the river course during the pre monsoon, south west monsoon and north east monsoon periods in 2010 to 2012. Sampling segments were chosen according to prevailing land use. A socioeconomic survey on agricultural practices was conducted to collect information on the type, time and quantity of fertilizer application.Our results indicate (i) little human activities in the forest segment resulted in a low nutrient yield; (ii) pilgrim activities led to high ammonium and phosphate yields in the temple segment; (iii) specific fertilizer management resulted in moderate and maximum nitrate yields in the respective agriculture segments. Annual NPK fertilizer inputs to the catchment were 95kgha−1yr−1.The average yield for the Pamba River catchment amounted to 3.5kgha−1yr−1 of DIN and 0.2kgha−1yr−1 of phosphate-P. As opposing predictions for densely-populated regions the N and P yields of the Pamba River are moderate to low on a global scale. It highlights the need for land use specific quantitative estimates from tropical regions in order to improve the global database and local water quality management.