Stream Order Research Articles

Local environment and fragmentation by drought and damming shape different components of native and non-native fish beta diversity across pool refuges

Pool refuges are critical for maintaining stream fish diversity in increasingly intermittent streams. Yet, the patterns and drivers of beta diversity of native and non-native fish in pool refuges remain poorly known. Focusing on Mediterranean streams, we decomposed beta diversity of native and non-native fish into richness difference (RichDiff) and species replacement (Repl), and local (LCBD, LCBDRichDiff and LCBDRepl) and species (SCBD) contributions. We assessed the influence of environmental and spatial factors associated with drought and damming fragmentations on beta diversity components and LCBDs, and of local species richness and occupancy on LCBDs and SCBD, respectively. Overall, non-native species showed a more limited occupancy of pool refuges than native fish. RichDiff dominated beta diversity, though it was influenced by drought and damming fragmentations for native fish and local environment for non-native fish. Repl for native fish was slightly influenced by local environment, but for non-native fish was largely driven by drought and damming, albeit with a contribution of local environment as well. LCBD and LCBDRichDiff increased in pools in low order streams for native fish and at low elevations for non-native fish, and with high or low species richness. SCBD was higher for native species with intermediated pool occupancy, but for non-native species with low occupancy. Our results suggest that stream fragmentation may drive native species loss and non-native species replacement in pool refuges, and that environmental filtering may shape non-native species loss. Pools in lower order streams harbouring unique species-rich or species-poor assemblages should be prioritize for conservation and restoration, respectively, and pools at low elevation with unique non-native assemblages should deserve control efforts. We encourage the partitioning of beta diversity and individual analysis of native and non-native fish in intermittent streams, which may be key in stressing the importance of pool refuges in safeguarding native fish diversity.

Exploring landscape and geologic controls on spatial patterning of streambank groundwater discharge in a mixed land use watershed

AbstractPreferential groundwater discharge features along stream corridors are ecologically important at local and stream network scales, yet we lack quantification of the multiscale controls on the spatial patterning of groundwater discharge. Here we identify physical attributes that best explain variation in the presence and lateral extent of preferential groundwater discharges along two 5th order streams, the Housatonic and Farmington Rivers, and 32 1st to 4th order reaches across the Farmington River network. We mapped locations of preferential groundwater discharge exposed along streambanks using handheld thermal infrared cameras paired with high‐resolution topographic and land use land cover datasets, surficial soil characteristic maps, and depth‐to‐bedrock geophysical measurements. The unconfined Housatonic River, MA, USA (12 km) had fewer discharge locations and less lateral extent (41 discharge locations with 38 m of active discharge/km of river) compared to the partially confined Farmington River, CT, USA (26 km; 169 discharge locations with 129 m of active discharge/km of river). Using a moving window analysis, we found along both rivers that discharge was more likely to occur where bank slopes were steeper, floodplain extent was narrower, and degree of confinement was higher. Along the Farmington River, groundwater discharge was more likely to occur where saturated hydraulic conductivity was higher and depth‐to‐bedrock was shallower. Among the 32 stream reaches surveyed (33.2 km of total stream length) within the Farmington River watershed, preferential discharge was observed in all but two stream reaches, varied from 0 to 25% of lateral extent along stream banks (mean = 6%), and was more likely to occur where stream reach slopes were steep, saturated hydraulic conductivity was high, and watershed urbanization was low. Our results show that, though both surface (e.g., topographic, land use land cover) and subsurface (e.g., soil characteristics, bedrock depth) factors control the prevalence of streambank preferential groundwater discharge, the dominant controls vary across valley settings and stream sizes.

Fish conservation in streams of the agrarian Mississippi Alluvial Valley: conceptual model, management actions, and field verification

The effects of agriculture and flood control practices accrued over more than a century have impaired aquatic habitats and their fish communities in the Mississippi Alluvial Valley, the historic floodplain of the Lower Mississippi River prior to leveeing. As a first step to conservation planning and adaptive management, we developed and tested a conceptual model of how changes to this floodplain have affected stream environments and fish assemblages. The model is deliberately simple in structure because it needs to be understood by stakeholders ranging from engineers to farmers who must remain engaged to ensure effective conservation. Testing involved multivariate correlative analyses that included descriptors of land setting, water quality, and fish assemblages representing 376 stream samples taken over two decades and ranging in Strahler stream order from 1 to 8. The conceptual model was adequately corroborated by empirical data, but with unexplained variability that is not uncommon in field surveys where gear biases, temporal biases, and scale biases prevent accurate characterizations. Our conceptual model distinguishes three types of conservation actions relevant to large agricultural floodplains: reforestation of large parcels and riparian zone conservation, in-channel interventions and connectivity preservation, and flow augmentation. Complete restoration of the floodplain may not be an acceptable option to the agriculture community. However, in most cases the application of even the most basic measures can support the return of sensitive aquatic species. We suggest that together these types of conservation actions can bring improved water properties to impacted reaches, higher reach biodiversity, more intolerant species, and more rheophilic fishes.

Understanding the spatial dynamics of values and disvalues in the Kaskaskia River Watershed, USA through a social-ecological lens

ABSTRACT Maintaining a resilient and sustainable agro-production system is replete with challenges, because management practices designed to enhance productivity can overlook the range of values derived from ecosystems and concerns about their future. Further complicating the decisions being made about agricultural settings is the variation in social-ecological stressors that shape how diverse community members interpret landscape change. We engaged residents of the Kaskaskia River Watershed in Illinois, USA in discussions about agroecosystems through participatory mapping exercises and focus groups. The spatially explicit data that were derived from this process were then modeled in relation to changes in watershed hydrology simulated using a Soil and Water Assessment Tool (SWAT) model. We observed that the four most salient ‘values’ associated with the watershed were recreation, erosion protection, crop production, and flood control. Erosion, siltation and sedimentation, increased flooding, and invasive species were considered the most relevant ‘disvalues’ because they represented the social-ecological stressors of greatest concern. Respondents believed that the values from ecosystems were more spatially clustered than disvalues, and the main river corridor was at greater risk of degradation than the associated tributaries despite these second order streams being more biologically diverse. The use of participatory mapping data coupled with SWAT to simulate changes in systemic responses of the watershed provided a social-ecological basis for identifying high and low-priority locations at a regional scale. Our results therefore aim to spatial prioritize and guide evidence-based decisions anchored in the social and ecological complexities of a Midwestern watershed.

Prioritization of watershed using morphometric parameters through geospatial and PCA technique for Noyyal River Basin, Tamil Nadu, India

Abstract Watershed management is essential for ensuring the availability of water for sustainable development. In the current study, the geospatial technique is utilized to prioritize the sub-watershed of the Noyyal River Basin to control soil erosion and propose water conservation measures. The study describes the importance of using a digital elevation model to evaluate the drainage pattern and to extract relevant parameters. The river basin was categorized into 17 sub-watersheds, designated as SW1–SW17. The stream order of watershed ranges from first to fifth order and possesses a dendritic drainage pattern. Thirteen fundamental morphometric parameters classified as linear, areal, and relief aspects were considered for the Noyyal River Basin. Principal component analysis (PCA) was performed in the current study for categorization and the morphometric parameters were correlated. PCA analysis is a more appropriate, well-known, commonly used method for having versatility in selecting more significant parameters (correlated parameters) that are responsible for watershed prioritization. The sub-watershed with the lowest compound value is ranked first in priority. It reveals that sub-watershed SW8 has a high priority while low priority is given to sub-watershed SW17. According to the results, more water and soil-conserving measures are suggested in the respective sub-watersheds.

Temporal change in urban fish biodiversity-Gains, losses, and drivers of change.

Our aim was to examine temporal change in alpha and beta diversity of freshwater fish communities in rivers that have urbanized over the same period to understand the influence of changes in land use and river connectivity on community change. We used biological (2001-2018), land use (2000-2015), and connectivity data (1987-2017) from Toronto, Ontario, Canada. We used linear mixed effects models to determine the strength of upstream land use, connectivity, and their changes over time to explain temporal change in alpha and beta diversity indices. We examined beta diversity using the temporal beta diversity index (TBI) to assess site-specific community change.The TBI was partitioned into gains and losses, and species-specific changes in abundance were assessed using paired t-tests. There were more gains than losses across the study sites as measured by TBI. We found little to no significant differences in species-specific abundances at aggregated spatial scales (study region, watershed, stream order). We found different relationships between landscape and connectivity variables with the biodiversity indices tested; however, almost all estimated confidence intervals overlapped with zero and had low goodness-of-fit. More fish biodiversity gains than losses were found across the study region, as measured by TBI. We found TBI to be a useful indicator of change as it identifies key sites to further investigate. We found two high value TBI sites gained non-native species, and one site shifted from a cool-water to warm-water species dominated community, both of which have management implications. Upstream catchment land use and connectivity had poor explanatory power for change in the measured biodiversity indices. Ultimately, such spatial-temporal datasets are invaluable and can reveal trends in biodiversity useful for environmental management when considering competing interests involved with urban sprawl in the ongoing "Decade on Restoration."

Flood Risk Vulnerability Detection based on the Developing Topographic Wetness Index Tool in Geographic Information System

Finding vulnerability to flooding locations is a crucial part of sensible urban development and effective natural disaster management. Globally, there has been a noticeable rise in the frequency of floods in recent years, which affects human habitation and several economic sectors. This calls for the employment of various prevention measures, wherein the assessment of vulnerability to flooding is crucial. The main objective of the present study is to introduce the best procedure for the identification of flood risk vulnerability detection using geographical information systems techniques and decision-making, based on a comparative evaluation of various scenarios. In this context, The current study will develop a Topographic Wetness Index (TWI) tool for the detection of these risks which can deal with the stream orders, calculate the length of the valley, and then show the outputs by thematic maps. The procedure with the developed adaptive tool has been applied to identify Flood Risk Vulnerability in Erbil city and some surrounding areas. The results of this paper indicated the existence of different levels of the TWI, which were classified into five classes. The procedure of this study has an advantage over other traditional methods since it takes into account mainly statistics data that are linked to the TWI which can be easily customized in detecting risk Vulnerability.

A statistical-based geospatial approach to prioritize the watersheds for soil erosion conservation in the Upper Awash Basin (Upstream Koka), Ethiopia

The current study focuses on the Upper Awash basin's morphometric parameters to understand the watershed's hydrologic characters with respect to soil erosion conservation. A correlation analysis based on a weighted sum approach was adopted to address the objectives of this research. The drainage patterns were extracted from SRTM-DEM (Shuttle Radar Topography Mission-digital elevation model), and ‘Stahler’s method’ was adopted to determine the stream order. The standardized formulas were employed to calculate about 23 different morphometric parameters. The Upper Awash basin (Koka) has been classified into six watersheds (WS-1 to WS-6). There are eleven selected variables, namely bifurcation ratio (Rb), drainage/stream frequency (Fs), drainage density (Dd), texture ratio (T), drainage texture (If), length of overland flow (Lo), form factor (Ff), shape factor (Bs), elongation ratio (Re), compact coefficient (CC) and circularity ratio (Rc) were used for prioritization ranking and categorization. The study has inferred four categories: very high, high, medium, and low, using the quartile statistical method and weighted compound value. Soil erosion is a major concern in watersheds composed of weak igneous rocks such as ignimbrite and holocene sediments such as limestone, conglomerate, sand, silt, and clay. Hence, three watersheds (WS-4, WS-5, and WS-6) with 53 % of the area have been identified as having strong soil erosion potential, representing very high and high categories requiring immediate conservation measures. Soil erosion conservation efforts and water resource management initiatives will benefit greatly from this effort. In addition, this study confirms that environmental studies utilizing a statistical approach based on GIS (geographical information system) are highly beneficial.

Quantitative analysis of hydropower potential in the upper Beas basin using geographical information system and MIKE 11 Nedbor Afrstromnings Model (NAM)

AbstractThe present study aims to identify potential locations for small‐scale hydroelectric power (HEP) stations in hilly regions for the purpose of generating renewable energy. A rainfall‐runoff (R‐R) model of the Beas River catchment was established using the MIKE 11 NAM to estimate the available discharge. The model was calibrated and validated over the period of June‐2015–May‐2018 and June‐2018–May‐2020, respectively, using daily observed discharge data at the Pandoh Dam site. The model exhibited good performance with a coefficient of determination (R2) of 0.82 during calibration and 0.70 during validation and a water balance of −0.01% and −18%, respectively. However, Lmax, CK1, CK2 and CQOF are found most sensitive parameters during the calibration. Further, thirteen major streams of order five or higher were selected for the assessment of hydropower potential, resulting in the identification of 131 potential run‐of‐river (ROR) hydropower sites. The hydropower potential at two proposed sites, Bhang SHEP (9 MW) and Raison SHEP (18 MW), was estimated to be 11 and 15 MW, respectively, using 90% dependable flow. The results demonstrate the effectiveness of using Digital Elevation Model (DEM) and Geographic Information System (GIS) techniques for determining hydropower potential in ungauged basins in the Himalayas.

Assessing Hydropower Potential in Nepal's Sunkoshi River Basin: An Integrated GIS and SWAT Hydrological Modeling Approach.

This study assessed the hydropower potential of a mountain watershed within the Sunkoshi River basin in Sindhupalchok, Nepal, utilizing geographic information systems (GIS) and the soil and water assessment tool (SWAT) hydrological model. Topographical, soil, land use, meteorological, and discharge data were employed to assess the study area for the appropriateness of hydropower generation. SWAT was utilized to delineate the Sunkoshi basin into 23 distinct subbasins and involved the creation of a detailed river network, incorporating various hydrological attributes including stream links, stream order, stream length, and slope gradient. After that, it was employed to simulate river discharges within these subbasins. The Sequential Uncertainty Fitting Version 2 (SUFI-2) algorithm, integrated within the SWAT Calibration and Uncertainty Program (SWAT-CUP), was employed to calibrate and validate the model. This step involved the adjustment of 25 selected parameters to enhance the model's accuracy and reliability in representing the hydrological processes of the Sunkoshi basin. Model performance was assessed utilizing three well-established efficiency criteria: coefficient of determination (R2 = 0.79), Nash-Sutcliffe efficiency (NSE = 0.73), and percent bias (PBIAS = 17.59). The study identified 36 sites across streams of order 3, 4, and 5 as having potential for hydropower generation. The hydropower potential at each identified site was evaluated using estimated stream flow and topographical head at various probability of exceedance (PoE) levels (40%, 45%, 50%, and 60%). The aggregate hydropower potential of the basin was quantified, yielding a potential of 371.30 MW at a 40% PoE. The findings suggest that an integrated approach combining SWAT-based hydrological modeling within a GIS can accurately assess a river basin's hydropower potential and provide insights into further evaluation of the comprehensive environmental assessment of the fragile Himalayan watersheds.

Land use characteristics affect the sub-basinal scale urban fish community identified by environmental DNA metabarcoding

The heterogeneity of urban landscapes has effects on the environmental characteristics and fish composition of individual urban streams, even within a single water system. It is, therefore, imperative to assess the influence of physiochemical properties on urban streams by analyzing the spatial distribution of fish communities at the local scale. However, conventional fish surveys encounter time and labor constraints when selecting and surveying dense sampling points under 2 km in stream networks. In this study, environmental DNA (eDNA) metabarcoding was used as an innovative survey methodology to identify the effects of land use and stream order on fish composition and tolerance guild in an urban area. The eDNA sampling was conducted in 31 sites of the Anyang stream network in Korea, including part of the stream undergoing ecological restoration. The eDNA survey detected 12 of 17 species (70.6%) that appeared in the historical data, and 12 of 18 species (66.7%) identified in a conventional field survey with kick nets and casting nets. The proportions of urban area, forest and grassland were positively correlated with abundance (p < 0.05) and richness (p < 0.05) in multiple regression analyses, while the proportion of agricultural area showed a negative correlation (p < 0.05). For abundance, richness, and diversity within the fish community from first- to third-order streams, there was a significant decrease in sensitive species (p < 0.05) alongside a significant increase in tolerant species (p < 0.01) across all three indices. The results of this study highlight variations in fish composition across sites within the local scale of the urban stream network, underscoring the need for detailed monitoring to understand the ecological function of urban streams.

Drainage Morphometric analysis of Yagachi watershed area, Karnataka State, India

The Yagachi River watershed in Karnataka State has been chosen for a thorough analysis to recognize the drainage system, morphometric features, and vulnerability of the watershed area to erosion. As a prerequisite to the analysis of morphometric features utilizing ArcGIS software, the stream networks and sub-watersheds (viz., SW01, SW02, SW03 and SW04) were delineated by making use of topographic sheets and the Digital Elevation Model (DEM). Yagachi watershed covers an area of 551.45 sq. km and observed predominant drainage patterns are sub-parallel and dendritic with sixth-order drainage. Higher stream orders (U=6), implying greater surface runoff and sediment load, and low mean stream length values in the upper reaches, signifying youthful morphological development and strong erosion potential, are characteristics of streams in the watershed. Drainage density values (1.262 to 1.930 km/km2), particularly at upper reaches in the NW part of the watershed, fine to very fine drainage texture values (7.572 and 8.337), moderate to high values of length of overland flow (Lg) and constant of channel maintenance (CCM) indicate steep to moderate slopes, fairly significant surface runoff, and high erosive power of the streams and greater sediment load. The elongated form of the watershed is shown by the computed lower form factor (Ff) and elongation ratio (Re) values. Relief characteristics of the watershed area, although suggest that the study area is vulnerable to erosion and in youth stage, in reality, the area is characterised more by the features of the late mature stage of landform development. The observed anomaly is attributed to the mountain-plain environment as the steeply sloped hill ranges of Bababudan formations are located in the northwestern parts of the Yagachi watershed area. However, the sub-watershed SW03 with high stream length, drainage density and relief value with fine drainage texture is relatively more susceptible to erosion.

Assessment of stream order and drainage pattern of flood prone areas of Ebonyi state, Southeastern Nigeria

This study evaluates stream order and drainage pattern of flood in Ebonyi state, Southeastern Nigeria. The drainage network within Ebonyi State was identified using the Shuttle Rader Topographic Mission (SRTM), the stream order and flood drainage pattern with the aid of the Digital Elevation Model (DEM), and the Topographic analysis of Spatial Analyst on Hydrology. The data was acquired using Geometric Positioning and the LANDSAT downloaded from the United States Geological Survey (USGS) Earth Explorer 2019 and Thematic Mapper (TM) 2009. The result shows that the map of the eastern part of Ebonyi State houses the Cross River basin as a main consequent river draining to the Atlantic Ocean. The drainage gets darker down the slope as more volumes of water move into the traversing drainage channels in their corresponding orders. As flood magnitude increases, the velocity decreases because more water from different river orders or tributaries has been added to the adjusting river channels. It proves that consequent rivers like the Enyim River of Izzi, Iyiokwu River of Abakaliki, Alcor River of Ikwo, Iyere River of Afikpo South, and Esu Umuchimaewuze River of Ohaozara Local Government areas slope down through the adjourning tributaries when the basin is saturated. The map legend shows a thick blue outcome indicating that the flood originates from the Enyim River of Izzi, Iyiokwu River of Abakaliki, Alchor River of Ikwo, Iyere River of Afikpo South, and Esu Umuchimaewueze River of Ohaozara. Therefore, urgent adjustments and construction of drainage systems are needed to accommodate more water volumes.

Ecological importance of low-order streams to macroinvertebrate community composition in Afromontane headwater streams

Low-order streams contribute to the abiotic and biotic character of large rivers and are renowned for harboring unique forms of aquatic flora and fauna. However, most studies on headwater streams mainly focus on the mainstems and overlook the contribution of the tributary systems. Moreover, low-order streams are generally overlooked in legislation and bioassessment programs, and consequently not protected in many countries. To contribute to the recognition of the ecological importance of low-orders streams, this study focused on determining whether river network characteristics and associated physico-chemical parameters can be used to effectively predict the variabilities in macroinvertebrate assemblage characteristics between first-order and second-order streams in the headwaters of the Nzoia River Basin, Kenya. The study quantified the structural and functional community composition, diversity, similarity, and richness of macroinvertebrate communities between the two river systems. Dissolved oxygen, coarse particulate organic matter, conductivity, stream width, depth, discharge and flow velocity were the main predictors of the diversity and distribution of macroinvertebrates in the first order and second-order streams. The first order streams recorded higher abundance of macroinvertebrates than the second-order streams. Taxa from families Ephydridae, Elmidae, Gomphidae, and genera Euthraulus, Neoperla, Orthothrichia and Prosopistoma were limited to the second-order stream sites while families Ceratopogonidae, Pisuliidae, Dytiscidae and genus Trichosetodes occurred exclusively in the first-order stream sites. Collector-filterers and collector-gatherers were the most abundant functional feeding groups (FFGs) in the two river systems. Scrapers were abundant in the second-order stream while shredders were abundant in the first order streams. The distinctness in the structural and functional composition of macroinvertebrates between the two river systems suggests that linkages among streams in a network as exemplified in the Nzoia River Basin, support and foster biodiversity.

Geomorphology and Morphometry of the Uttar Mand River Basin, Satara District, Maharashtra, India

In the present investigation various morphometric parameters of the Uttar Mand river basin are outlined. The Survey of India Toposheet numbers 47 G/15, 47 K/3 on the scale of 1: 50,000 were used for the present study. Stream ordering method as suggested by the Strahler has been employed. According to morphometric analysis of the Uttar Mand river basin, it is a fifth-order basin that is transitioning from an early mature to an older stage of the fluvial geomorphic cycle. The drainage pattern of the basin is dendritic in nature. A particular order's mean channel segment length is more than the next lower order but less than the next higher order. The relationship between stream order and mean stream length provides a group of points that lie roughly along a curve line, indicating that the area is not subject to severe structural influence.

Prioritization of sub-watershed through morphometric analysis, Principal Component, and Land Use/Cover: A Case study of Cachar District, India

Soil and watershed management relies heavily on watershed prioritization. Examining flood risk assessment using morphometric parameters and land use/land cover (LULC) datasets analyzed using GIS, this study focuses on watershed prioritization in the Cachar district. To calculate linear, areal, and relief morphometric parameters and to demarcate sub-watersheds, a 30 m resolution ALOS DEM was used. To evaluate LULC parameters, we also used Esri LULC 2023, which is based on Sentinel-2 imagery with a resolution of 10 meters. To establish priorities, an integrated method based on Principal Component Analysis (PCA) was used. When it comes to watershed prioritization, principal component analysis (PCA) is well-known for its adaptability and efficiency in choosing important correlated parameters. Priority was given to the sub-watershed that had the lowest compound value. Stream orders varied from 2 to 4, and the district was subdivided into 6 sub-watersheds. With a stream order of 4, sub-watershed 5 (SW_5) had the highest order, and sub-watershed 4 (SW_4) had the lowest.

A method for evaluating sediment-induced macroinvertebrate community composition changes in Idaho streams.

Human activities can increase sediment delivery to streams, changing the composition, distribution, and abundance of stream aquatic life. Few U.S. states have numeric water quality standards for streambed sediment under the Clean Water Act, so managers often need to develop local application-specific benchmarks. This study developed stream surface fine sediment <2 mm (sand and fines, SF) and macroinvertebrate fine sediment biotic index (FSBI) benchmarks and an application framework to test for sediment-induced macroinvertebrate community composition changes in 1st-4th order Idaho streams. FSBI reference benchmarks were calculated as the 25th percentile FSBI value among reference sites within three ecoregion-based site classes. Two approaches were used to develop SF benchmarks. Quantile regression was used to define reach-specific SF benchmarks representing an upper bound value expected under reference conditions. In addition, logistic regression was used to predict SF values with 50% and 75% probability that FSBI is worse than reference within each stream order and site class. The strength of association between SF benchmarks and macroinvertebrate community condition was evaluated by calculating relative risk using multiple datasets and examining responses of multiple macroinvertebrate indicators to SF benchmark status. SF reference benchmarks generally had stronger associations with poor macroinvertebrate condition than SF stressor-response benchmarks. Across datasets and macroinvertebrate indicators, poor macroinvertebrate condition was 1.8-3 times more likely when SF reference benchmarks were exceeded than when achieved. We propose rating the strength of evidence for a surface fine sediment-induced macroinvertebrate community composition change at the sample event scale as 'unlikely' if both SF and FSBI reference benchmarks are achieved, having 'mixed evidence' if only one reference benchmark is achieved, and 'likely' if both reference benchmarks are not achieved. We recommend combining ratings with other relevant data in a weight-of-evidence approach to assess if sediment impairs aquatic life.

Seeking for gaps in taxonomic descriptions of endemic fishes: a pathway to challenge the Linnean shortfall in a Neotropical basin

Abstract The Tocantins-Araguaia River basin hosts an elevated number of fish species, and new species have been continuously described. In this basin, we investigated patterns of endemic fish species descriptions examining their association with species distribution range, altitudinal gradient, fluvial hierarchy of watercourses, and sampling effort. For each species, we collected its year of taxonomic description, geographical coordinates of its holotype, body size (a proxy for species range), fluvial hierarchy of watercourses, and both altitude and sampling effort related to the locality of the holotype. The number of taxonomic descriptions was positively correlated to sampling effort, and better-sampled regions accumulated more descriptions over time. Moreover, altitude was positively correlated to the year of species description, whereas body size was negatively correlated to it. While species with recent descriptions were more associated to first to third order streams, species with recent and older descriptions were associated to high-order rivers. Therefore, fish species with broader distributions tend to have older descriptions in regions of lower altitude, whereas species with restricted distributions recent descriptions at higher altitudes. Increasing efforts in the upper regions of the Tocantins-Araguaia basin seems to be a good and fruitful strategy for reducing the Linnean shortfall.

Real-time flood inundation monitoring in Capital of India using Google Earth Engine and Sentinel database

This study focuses on researching flood inundation and vulnerable areas in Delhi NCT using Remote Sensing (RS) and GIS techniques during flood from July 8 to July 15, 2023, with the entire analysis conducted through satellite and cloud-based processing methods, specifically employing the Google Earth Engine (GEE). Leveraging high-temporal satellites that gather data enables the identification of flooded zones in real-time, during floods, and in the aftermath. Analyzing data collected at different stages of a flood provides valuable insights for pinpointing affected areas. Water naturally flows from high to low elevation areas, and based on elevation data, lowest elevation regions, particularly along the Yamuna riverbank under Delhi NCT, are highly susceptible to flooding, are considered flood-prone areas and flood water inundated. A thorough comprehension and flood-prone area mapping, along with a map illustrating highly inundated zones. After obtaining flood inundation maps and overlaying them with Land Use and Land Cover (LULC) classified maps, the study identified specific areas that experienced flood inundation. The analysis generated a flood zone map, indicating that the flooded area encompasses approximately 110 km², within a total study area of 1488.4 km². The affected areas have elevations ranging from 200 to 210 meters, whereas the maximum elevation in the study area is approximately 326 meters. The GEE platform is employed for processing, utilizing a Supervised classification algorithm for LULC mapping, and an Inverse Distance Weight method for mapping temperature and rainfall. This study utilized the GEE platform to create pre- and post-flood maps based on Sentinel 1 satellite datasets. Generated DEM, and employed it to create various surface estimation maps, including a stream order map. The GIS is employed to enhance the efficiency of monitoring and managing flood disasters, with the high temporal and spatial resolution data playing a pivotal role in flood monitoring.

Quantitative morphometric analysis of streams in extreme humid areas a case study of the Um-Mawiong river basin, Mawsynram, Meghalaya

Quantitative morphometric analysis of the drainage system is essential to characterising a watershed, as all the hydrologic and geomorphic processes occur within the watershed. Consequently, this plays a crucial role in understanding the geo-hydrological attributes of a drainage basin to the terrain feature and its flow patterns, thus enabling the estimate of the incidence of infiltration and runoff and other related hydrological characteristics of a watershed, which strongly impacts natural resource conservation. The study area selected is the Um-Mawiong River basin in Mawsynram, Meghalaya. The basin shows a dendritic pattern that highlights the homogeneity in the texture of the basin. Results suggest that the stream frequency of the basin is 19.10 km², suggesting a faster surface runoff and less infiltration. In addition, it has an Elongation ratio of 0.75 indicating an elongated basin shape. The current study demonstrates that the implementations of GIS techniques are trustworthy, efficient, and capable of managing extensive databases for managing river basins. The present study tries to analyse the linear, areal and relief aspects of the basin using a GIS environment and manipulated for different calculations. The analysis reveals that the total number of stream segments and length are maximum in first-order streams and decrease as stream order increases. The drainage density exhibits a high degree of positive correlation, i.e., 0.87, with its frequency suggesting an increase in stream population concerning increasing drainage density and vice versa.