Total Basin Area Research Articles

Human-made small reservoirs alter dryland hydrological connectivity

Our research shed light on the distribution, number, and impact of small reservoirs (SRs) on rural dryland water availability and hydrology. We measured the storage capacity, relationship to environmental variables, and effects on the hydrology of all SRs (1225) found within a Sonoran Desert basin. SRs were predominantly associated with Tertiary conglomerates and Quaternary alluvium and were less common in extrusive rocks. A higher concentration of reservoirs was observed in woodlands and thornscrub, with fewer SRs in desertscrub than anticipated by chance. The average size of these small reservoirs was 5205 m2. All SRs reached full storage capacity during the rainy season, but only 20 % retained water throughout the year. Furthermore, our analysis revealed a significant impact on basin connectivity, with only 41 % of superficial drainage being connected. Notably, two large dams were found to disconnect 26 % of the basin. Despite their relatively small watershed footprint, SRs were found to be responsible for disconnecting 33 % of the total basin area. The magnitude of rainfall events played a crucial role in connectivity dynamics. Low-magnitude rainfall events led to sediment retention in SRs, reducing connectivity, while moderate events increased connectivity by repeatedly filling SRs. High-magnitude events reshaped channels, transported sediments, and enhanced overall connectivity. The concentration of SRs in the upper reaches of the basin coincides with higher stocking rates. SRs, are relatively recent additions to desert landscapes, impacting ecological dynamics. Their construction and use fragment an already disjointed basin, thereby restricting water retention by larger dams. These findings emphasize the intricate relationship between SRs, rainfall occurrences, and the overall connectivity of the basin. We underline that documenting the cumulative effects of SRs yields valuable insights for managing water resources in arid ecosystems.

Integrating remote sensing classification techniques for land use mapping in semi-arid regions: a case study of the Tamlouka basin, Algeria.

Worldwide, the majority of countries are actively devising strategies to address the challenges associated with unregulated and unmanageable development, the decline in environmental quality and the depletion of valuable agricultural land. This has led to a growing emphasis on understanding land use and land cover. In order to determine a better land use policy, legislators and planners need to know the current distribution of agricultural and urban lands, as well as information about changes in their proportions. Our approach combines data centred on main four themes-geology, slope gradient, hydrographic network and land use-in order to exploit classifier complementarities in our targeted agricultural study area of Tamlouka Basin, Algeria. Landsat 8 OLI-TIRs multispectral imagery and Shuttle Radar Topography Mission (SRTM-1arc v3) were used experimentally for classification and Digital Elevation Model (DEM) analysis. The classification's accuracy is confirmed by comparing the results of the decision tree classification with the validation samples. Results of the combination of several maps of classifications from the different methods show that the Tamlouka alluvial plain, having an area of 19,300 ha and an average slope gradient of less than 2°, drains the elevated reliefs that surround it via hydrographic network. The plain occupies 37% of the total basin area, with over of 60% being used for crop cultivation, regardless of fallow land areas in agricultural rotation at that time. The slope has been identified as a crucial factor determining land use patterns in the study area. This result can be used in prospective watershed management.

Prioritization of soil erosion-prone sub-watersheds using geomorphometric and statistical-based weighted sum priority approach in the middle Omo-Gibe River basin, Southern Ethiopia

ABSTRACT Soil erosion, a major factor contributing to land degradation, poses significant environmental challenges across sub-Saharan Africa, including Ethiopia. This study identifies erosion-prone sub-watersheds in southern Ethiopia's middle Omo-Gibe River basin using digital elevation model data, analyzed using a geomorphometric and statistically weighted sum priority approach in a Geographic Information System environment. Additionally, hypsometric analysis, lithology, land use/cover analysis, and field observations were integrated to enhance methodological reliability in assessing soil erosion patterns and subsequent land degradation in the basin. Results highlight sub-watersheds with varying degrees of erosion sensitivity, emphasizing morphometric parameters and landscape characteristics. Furthermore, hypsometric analysis confirms a moderate to high susceptibility of sub-watersheds to soil erosion. Moreover, half of the river basin consists of shrubland, encompassing scrubs, range lands, and small wooded areas. These are less efficient in mitigating erosion compared to forests, especially in the face of significant summer rainfall and ensuing runoff. Statistical prioritization identified 19 sub-watersheds, covering 43% of the basin's total area, as highly prone to soil erosion and land degradation. The study's findings are valuable for Ethiopian watershed management decision-makers, enabling informed resource allocation and targeted interventions to control soil erosion and protect water resources by utilizing the outputs of this study.

Implications of Accuracy of Global Glacier Inventories in Hydrological Modeling: A Case Study of the Western Himalayan Mountain Range

Alpine glaciers are a fundamental component of the cryosphere and are significantly sensitive to climate change. One such region is the Hindukush Karakoram Himalaya (HKH) and Tibetan Plateau (TP) region, which contains more than 40,000 glaciers. There are more than 12 glacier inventories available covering parts of (or the entire) HKH region, but these show significant uncertainties regarding the extent of glaciers. Researchers have used different glacier inventories without assessing their accuracy. This study, therefore, assessed the implications of the accuracy of global glacier inventories in hydrological modeling and future water resource planning. The accuracy assessment of most commonly used two global glacier inventories (Global Land Ice Monitoring from Space-GLIMS v 2.0 and Randolph Glacier Inventory-RGI v 6.0) has been carried out for three sub-basins of the Upper Indus Basin—the Swat, the Chitral, and the Kabul River basins (combined, this is referred to as the Great Kabul River Basin)—with a total basin area of 94,552.86 km2. Glacier outlines have been compared with various Landsat 7 ETM+, Landsat 8, high-resolution Google Earth images, and manually digitized debris-covered glacier outlines during different years. The total glacier area for the Great Kabul River Basin derived from RGI and GLIMS is estimated to be 2120.35 km2 and 1789.94 km2, respectively, which was a difference of 16.9%. Despite being sub-basins of the Great Kabul River Basin, the Swat, and the Chitral River basins were different by 54.74% and 19.71%, respectively, between the two inventories, with a greater glacierized area provided by RGI, whereas the Kabul River basin was different by 54.72%, with greater glacierized area provided by GLIMS. The results and analysis show that GLIMS underestimates glacier outlines in the Swat and the Chitral basins and overestimates glacier extents in the Kabul River basin. The underestimation is mainly due to the non-representation of debris-covered glaciers. The overestimation in GLIMS data is due to the digitization of seasonal snow as part of the glaciers. The use of underestimated GLIMS outlines may result in 5–10% underestimation of glacier-melt contribution to flows in the Swat River basin, while an underestimation of 7% to 15% is expected in the Chitral River Basin, all compared to RGI v 6.0 outlines. The overestimation of glacier-melt contribution to flows in the Kabul River basin is insignificant (1% to 2%) using GLIMS data. In summary, the use of the GLIMS inventory will lead to underestimated flows and show that the Great Kabul River Basin (particularly the Chitral River Basin) is less sensitive to climate change effects. Thus, the current study recommends the use of RGI v 6.0 (best glacier inventory) to revisit the existing biased hydro-climate studies and to improve future hydro-climate studies with the concomitant rectification of the MODIS snow coverage data. The use of the best glacier inventory will provide the best estimates of flow sensitivity to climate change and will result in well-informed decision-making, precise and accurate policies, and sustainable water resource management in the study area. The methodology adopted in the current study may also be used in nearby areas with similar hydro-climate conditions, as well as for the most recently released RGI v 7.0 data.

Identifying sources of groundwater and recharge zone using stable environmental isotopes in the Erbil basin-northern Iraq

The Dashty-Hewler basin is a groundwater basin located in Erbil in northern Iraq. It comprises three distinct sub-basins (Kapran, Central, and Bashtapa) covering a total basin area of 2,660 ​km2. It is bounded by the greater Zab river to the north and the little Zab to the south. The groundwater in this catchment has never been investigated using modern environmental isotope evidence. Since the groundwater in this basin serves as both drinking water and a source of irrigation, its management is crucial. Recently, due to the increase in population, excessive pumping has taken place, which has led to a decline in the water table. Accordingly, it is necessary to address the issues of where the groundwater will recharge and what the source of the recharge will be. For this purpose, 27 groundwater samples from different wells and two river water samples were analyzed for stable isotopes (δ18O and δ2H). The distribution of δ18O and δ2H over the study area was utilized by inverse distance weighted (IDW) interpolation within ESRI ArcGIS (10.8). The results indicated that the relationship between δ18O and δ2H in the groundwater samples (δ2H ​= ​6.59 δ18O +7.48‰) showed relative shifts of both the slope and the deuterium excess when compared to the Iraq meteoric water line (δ2H ​= ​7.66 δ18O ​+ ​14.19‰). The deviation of data points from the meteoric line can be attributed to high evaporation both during the rainy season and through run-off on the ground surface before infiltration. Most of the groundwater samples had a deuterium excess above 10‰ between 12.14 and 22.72‰, suggesting the precipitation present in the groundwater comes from the Mediterranean sector. Based on local isotopic gradients (δ18O, −0.22/100 ​m), in combination with topographic and geologic criteria, the recharge areas were identified as being between 400 ​m and 1,100 ​m above sea level.

Runoff Simulation under the Effects of the Modified Soil Water Assessment Tool (SWAT) Model in the Jiyun River Basin

Few studies have been conducted to simulate watersheds with insufficient meteorological and hydrological information. The Jiyun River watershed was selected as the study area. A suitable catchment area threshold was determined by combining the river network density method with the Soil and Water Assessment Tool (SWAT) models, which was driven using the CMADS dataset (China Meteorological Assimilation Driving Datasets for the SWAT model). Monthly runoff simulations were conducted for the basin from 2010 to 2014, and the calibration and validation of model parameters were completed with observed data. The results showed that the final expression for the density of the river network in the Jiyun River basin as a function of density (y) and the catchment area threshold (x) was obtained as y = 926.782x−0.47717. The “inflection point” of the exponential function was the optimal catchment area threshold. The catchment area threshold had an upper and lower limit of the applicable range and was related to the percentage of the total basin area. The simulation results would be affected if the threshold values were outside the suitable scope. When the catchment area was 1.42% of the entire watershed area, increasing the threshold value had less effect on the runoff simulation results; decreasing the threshold value would cause the simulation results to be unstable. When the catchment area reached 1.42% to 2.33% of the total watershed area, the simulation results were in good agreement with the observed values; the coefficient of determination (R2) and Nash–Sutcliffe efficiency coefficient (NSE) were more significant than 0.79 and 0.78 for the calibration periods evaluation index. Both were greater than 0.77 and 0.76 for the validation period, which met the evaluation requirements of the model. The results showed that the CMADS-driven SWAT model applied to the runoff simulation and the river network density method adoption to determine the catchment area threshold provided a theoretical basis for a reasonable sub-basin division in the Jiyun River basin.

Projection of disaster-causing risk of extreme precipitation in the Yangtze River Basin based on CMIP6

Abstract Global warming will significantly affect the frequency and intensity of extreme precipitation and further affect the spatio-temporal pattern of disaster-causing risk of extreme precipitation. This study analyzes the spatio-temporal trends of extreme precipitation and projects its disaster-causing risk under different climate scenarios in the Yangtze River Basin from 2021 to 2100. The results indicate that the extreme precipitation in the Yangtze River Basin shows an increasing trend in the future. Annual precipitation (PRCPTOT) increases by 33.05–42.56% under five scenarios compared with the historical period. The future change in heavy precipitation (R95p) also shows a significant increase, but heavy rain days (R50) and 5-day maximum precipitation (RX5day) decrease. The disaster-causing risk of extreme precipitation in the Yangtze River Basin is mainly Levels III and IV, accounting for 57.23–65.99% of the total basin area. The area with Level V is mainly distributed in the Poyang Lake Basin and the lower main stream of the Yangtze River. Moreover, the changes in disaster-causing risk of extreme precipitation are mainly manifested in the decrease of areas with low risk (Levels I and II) and the increase of areas with medium risk (Levels III and IV) in different periods.

Spatiotemporal trends of NDVI and its response to climate variability in the Abbay River Basin, Ethiopia

Woody vegetation plays a vital role in regulating the water budget and energy exchange in the Earth's system. This study aimed at analyzing the spatiotemporal variability of Normalized Difference Vegetation Index (NDVI) and its response to Potential Evapotranspiration (PET), rainfall (RF), soil moisture (SM), and temperature (TEM) in the study area. The trends, correlations, and relationships between NDVI and climate variables were executed using Mann-Kendall monotonic trend (MKMT), partial correlation coefficients (PCC), and multiple linear regression (MLR) methods, respectively. Over the last 26 years, the interannual NDVI increased by 0.0065 yr−1 (R2 = 0.159, p = 0.157). The spatiotemporal MKMT and Theil-Sen slope analysis showed that interannual NDVI increased significantly in 78% of the basin's total area. Of the 78% of the basin, 31%, and 47%, of the total area showed extremely significant increasing (Zmk = 4.706, p ≤ 0.01), and significant increasing trends (Zmk = 2.378, p ≤ 0.05) respectively. The interannual variation of NDVI was well explained (R2 = 0.88, Adjusted R2 = 0.84) by the climate variables in the eastern, southeastern, and central sub-basins where agriculture, grass, sparse vegetation and barelands are the predominant land use land cover (LULC) classes. The main climatic factors that control vegetation growth and greenness during the rainy season were found to be PET, SM, and RF with 0.91, 0.99, and 0.86 PCC with NDVI respectively. The current study broadens the scientific community's understanding of the relationship between climate variables and vegetation growth in highland ecosystems. Understanding the seasonal and long-term relationship between climate and NDVI contributes to the scientific knowledge of highland ecosystems, which are extremely vulnerable to climate change.

The integration of RUSLE-SDR lumped model with remote sensing and GIS for soil loss and sediment yield estimation

As a major contributor of land degradation, water borne soil erosion poses a threat to environmental and socioeconomic sustainability worldwide. Recently, various anthropogenic factors have aggravated soil erosion related problems in most of the humid and semi arid parts of the developing countries like India. Therefore, accurate quantification of the spatially distributed soil erosion along with the identification of erosion hot spots is of paramount significance for designing extensive management strategies to combat erosion hazard. The present study aimed to estimate mean annual soil loss in a tropical river basin such as Kumari river basin (KRB, area: 195125 ha) in the Chotanagpur plateau region in India. In addition, the study also quantified mean sediment yield and identified the main sediment sources within the basin. For these purposes, the present study introduced a raster based spatially distributed approach that integrated RUSLE and sediment delivery ratio (SDR) models with remote sensing (RS) and GIS. The results depicted that annual soil loss within the basin varied from 0 to 208.34 t ha – 1 yr – 1 with an average of 1.92 t ha – 1 yr – 1. The computed annual soil loss was about 364.05 × 103 tonnes, of these, 209.46 × 103 (∼58 %) were lost from only 8.93 % of the total basin area at intolerable rate. Similarly, the estimated sediment yield within the basin ranged from 0 to 64.53 t ha – 1 yr – 1 with a mean of 1.15 t ha – 1 yr – 1 and followed a similar distribution pattern of soil erosion. Being characterized by steep topography, the forest patches in the upstream part of the basin showed the most critical erosion risk. The methodology adopted in the current research displayed acceptable correctness and enabled spotting of most vulnerable areas of water erosion and critical sediment sources, initiating a comprehensive anticipating aid for the implementation of proper land management and soil conservation plans. This perspective is surmised to be helpful for extensive study of water erosion in other tropical river basins.

낙동강수계 인공습지의 영양염 저류 효과

As projects for maintenance and restoration of the river basin ecosystem are implemented, a riverine ecobelt creation project is being promoted to purchase and restore land in the Nakdong River basin.
 This study analyzed the effects of nutrients retention at two artificial wetlands and one pot seedling restoration area created by the Nakdong River basin's riverine ecobelt creation project. By type of retention, the amount of nutrient stored by plants was the highest, and the amount of nutrient stored by land plants was higher than that of aquatic plants. The total amount of retention was the largest in september in all study sites. As a result of evaluating the nutrients retention effect of each study site, the reduction rate of pot seedling restoration area was the highest. And the result showed that pot seedling restoration area reduces nutrients by 10.19% of nitrogen, 58.89% of phosphorus out of the total nutrients loading, through the only 5.95% area of the total basin area. Considering the Nakdong River basin's riverine ecobelt creation project in terms of the nutrients retention effect, it is more appropriate for that purpose to promote planting-type creation projects such as pot seedling restoration.

Mapping Potential Soil Water Erosion and Flood Hazard Zones in the Yarlung Tsangpo River Basin, China

The ubiquity of soil water erosion in the Yarlung Tsangpo River Basin leads to a series of natural hazards, including landslides, debris flows and floods. In this study, the Revised Universal Soil Loss Equation model (RUSLE) was used to quantify potential soil water erosion, while the Height Above Nearest Drainage model (HAND) was used to delimit potential flood hazard zones. Remote sensing and geographic information system technologies were employed to spatialize the results, which showed that the annual soil loss from water erosion was less than 1239 t ha−1 y−1. The total soil loss was estimated to be over 108 × 106 tons, of which about 13 × 106 tons (12.04% of the total) occurred from the agricultural land in the downstream valley. Soil erosion mapping was performed using six levels of soil erosion intensity and the effects of precipitation, land use/land cover and topography on soil erosion were revealed. Increases in precipitation and slope gradient significantly increased the soil loss rate, while the maximum rate of soil loss occurred from densely vegetated land, reaching 9.41 t ha−1 y−1, which was inconsistent with erosion preconceptions for this land type. This may be due to a combination of the region’s unique climate of high intensity rainfall and steep slopes. Flood hazard mapping showed that all regional cities were located in a flood hazard zone and that, within the total basin area (~258 × 105 ha), 9.84% (2,537,622 ha) was in a high flood occurrence area, with an additional 1.04% in aa vulnerable to moderate flood hazard area. Approximately 1.54% of the area was in a low flood risk area and 4.15% was in a very low flood risk area. The results of this study provide an initial identification of high-risk soil water erosion and flood hazard locations in the basin and provide a foundation upon which decision-makers can develop water and soil conservation and flood prevention policies.

The Role of Boundary Mixing for Diapycnal Oxygen Fluxes in a Stratified Marine System

AbstractInsufficient diapycnal oxygen transport through the halocline is the key reason for the anoxic conditions typically observed in the deeper parts of the Baltic Sea. The variability of turbulent oxygen fluxes through the halocline was investigated seasonally and in space during three cruises (summer, fall, winter). Turbulence dissipation rates and oxygen fluxes showed a pronounced seasonal pattern, with the lowest values during summer. At the basin boundaries, halocline oxygen fluxes increased by an order of magnitude as a result of boundary mixing. A simple box model, distinguishing between interior, intermediate, and boundary regions, was used to extrapolate the locally observed fluxes to the central Baltic Sea. The boundary area, covering less than 23% of the total basin area, contributed more than 80% of the basin‐scale oxygen transport through the halocline. According to this model, the annual oxygen flux through the halocline is of the order of 20–28 Gmol per year.

Geospatial technology for assessment of soil erosion and prioritization of watersheds using RUSLE model for lower Sutlej sub-basin of Punjab, India.

Erosionofsoilby water coupled with humanactivitiesisconsideredas one of the mostseriousagents of land degradation, posing severe threat to agricultural productivity, soil health, water quality, and ecologicalsetup. Theassessment of soil erosion andrecognitionof problematic watersheds are pre-requisite for management of erosion hazards. In the present study, Revised Universal Soil Loss Equation (RUSLE) integrated with remote sensing (RS) and geographic information system (GIS) has been used to assess the soil erosion in lower Sutlej River basin of Punjab, India, and prioritize the watersheds for implementation of land and water conservation measures. The total basin area was about 8577 km2 which was divided into 14 sub-watersheds with the area ranging from 357.8 to 1354 km2. The data on rainfall (IMD gridded data), soil characteristics (FAO soil map), topography (ALOS PALSAR DEM) and land use (ESRI land use and land cover map) were prepared in the form of raster layers and overlaid together to determine the average annual soil loss. The results revealed that the average annual soil loss varied from 1.26 to 25 t ha-1, whereas total soil loss was estimated to be 2,441,639 tonnes. The spatial distribution map of soil erosion showed that about 94.4% and 4.7% of the total area suffered from very slight erosion (0-5 t ha-1year-1) and slight erosion (5-10 t ha-1year-1), respectively, whereas 0.11% (9.38 km2) experienced very severe soil loss (> 25 t ha-1year-1). Based on estimated average annual soil loss of sub-watersheds, WS8 was assigned the highest priority for implementation of soil and water conservation measures (323.5 t ha-1year-1), followed by WS9 (303.8 t ha-1year-1), whereas WS2 was given last priority owing to its lowest value of soil loss (122.02 t ha-1year-1). The present study urges that conservation strategies should be carried out in accordance with the priority ranking of diverse watersheds. These findings can certainly be used to implement soil conservation plans and management practices in order to diminish soil loss in the river basin.

Satellite remote sensing and GIS-based multi-criteria analysis for the assessment of groundwater potentiality in fractured limestone aquifer: Case study of Maknassy Basin, central Tunisia

Satellite remote sensing and GIS-based multi-criteria analysis are used to assess groundwater availability and potentiality of the fractured limestone aquifer of the Maknassy Basin, Central Tunisia. The integration of the multi-source data used (satellite images from Landsat 7 Enhanced Thematic Mapper Plus (ETM +), Digital Elevation Model (DEM), hydrology and borehole data) based on the multi-criteria analysis has led to the production of synthesis maps documents on the areas of hydraulic potentiality of the upper Cenomanian - lower Turonian aquifer in the Maknassy Basin. The distribution of major faults and lineaments was extracted from satellite images processed by several techniques. Lineaments analyses are widely included with geological and hydrogeological data in the selection of groundwater exploration sites. The combination of the four developed thematic maps (availability, accessibility, exploitability and productivity) gives a groundwater potential map of the studied aquifer. This map shows four classes of hydrogeological potential: (i) the poorly class occupies 22% of the total basin area and is concentrated at the West end of the basin; (ii) the moderate class (49%) is found in almost the entire basin; (iii) the good (15%) and (iv) the excellent class (14%) occupy the centre of the basin.

Estimation of the magnitude of soil and sediment erosion in the Yaraa Valley Basin using the

The Yaraa Valley Basin is part of the Hamrin Hills extending as a strip surrounding the sedimentary plain from the east, parallel to the Zagros Mountains and the Tonel Mountains in Iranian lands. The upper sources of the basin are those extending in Iranian lands, which receive more than 370 mm of rain annually from the humid climate that supplies the basin with water, In addition, the slope of more than 25 degrees, as well as the various geological formations, contributed to the nature of soil erosion in this basin. The aim of this research was to estimate the size of erosion and sediments transferred towards the mouth of the valley, as well as to find appropriate solutions to limit soil deterioration in this aspect. Geographical information and remote sensing in order to apply the equations of the EPM model, and the results extracted from the application of this model showed that the most important factors affecting the intensity of erosion depend on the topographical factor and the lithological factor as well as the change in land use, While the coefficient of Z for potential erosion was about 0.2-1.5, and the volume of erosion in the valley was about 63% of the total basin area, and this confirms that most of the basin area is exposed to severe erosion according to the EPM model.

Glacier inventory of the Subansiri River Basin in the Brahmaputra catchment using Landsat satellite data: A case study of the Daisaphu Glacier changes

Monitoring of glaciers of the Subansiri River Basin, regardless of geopolitical distribution, is pivotal, as the Subansiri River is one of the most important tributaries of the Brahmaputra River. However, the existing inventories in Eastern Himalayas mostly covered the Indian side, while most of the glacier regions are located in Tibet. For the first time, we constructed a complete, validated glacier and lake inventory using Landsat satellite data. We report 390 glaciers, where 191 are hanging glaciers, 59 ice aprons, 52 cirques, 40 niches, 37 valley glaciers, 9 icecaps and 2 outlet glaciers. The snow‐covered region occupies 0.96% of the total basin area. The study also reports that there are 52 glacial lakes, covering a cumulative area of 3.358 km2. Furthermore, the 37 valley glaciers cover an area of ~144 km2, with lengths ranging between 1.3 and 15.3 km, and a total ice reserve of ~11.95 km3. The largest glacier of the basin is the Daisaphu Glacier, which has an ice reserve of ~2.70 km3. We calculated the retreat of the Daisaphu Glacier to be 16 ma−1 between 1989 and 2014. However, the retreat has been seen to be enhanced, up to 21 ma−1 after 2009. We also estimated the recession rate of 27 other valley glaciers, apart from the Daisaphu Glacier. The recession rate of the glaciers ranges between 2 and 51 ma−1, where 30% of glaciers have retreated at a rate of <10 ma−1, 55% of glaciers have retreated at a rate of >10 ma−1 and 15% of glaciers show no frontal changes since 1985. The pro‐glacial moraine‐dammed lake of the Daisaphu glacier shows growth of 0.471 km2 in area, and an increase of 0.0833 km3 in water volume between 1978 and 2014. This inventory should help in the assessment of future water scenarios and climate change, as it will impact a large community downstream which is dependent on the glaciers which lie across two countries.

Physiographic Characterization of the Córrego do Perdido River Basin – Ibatiba/ES

The use of natural resources has been accompanied by serious problems appearing from inadequate management. Thus, knowing the characteristics of the environmental planning units can contribute to minimizing damage and planning conservationist actions. The morphometric characteristics of the Córrego do Perdido river basin were determined for environmental planning purposes. To this end, we used radar data from the Shuttle Radar Topography Mission (SRTM) to represent the Digital Elevation Model (DEM) and geoprocessing techniques in a Geographic Information System (GIS) environment. To elucidate the hydrological behavior of the basin, we estimated some morphometric parameters. The drainage area obtained corresponds to 31.11 km², and the perimeter measures 33.57 km. With an irregular shape, the basin presented a shape factor equal to 0.12, compactness coefficient of 1.69, circularity index of 0.347 and small flow extension (0.1052 km). The drainage density found was 2.38 km-2, indicating high drainage capacity. The basin had a strong wavy terrain (47.38% of the total basin area), with an average slope of 30.6% and an average altitude of 1,145 meters. The physiographic characterization revealed through the morphometric indices that the basin has an elongated shape and a dendritic drainage network of fourth order and, disregarding the adverse hydrological events, is not very susceptible to flooding. The high drainage capacity contributes to the infiltration of water into the soil, and the vegetation cover of the slopes must be preserved.

Modelling effects of forest fire and post-fire management in a catchment prone to erosion: Impacts on sediment yield

The present paper contributes to bridging the gaps in modelling post-fire impact and mitigation measures on soil erosion. The specific aims were to predict the effects of forest fires and post-fire mitigation measures on runoff and specific sediment yield (SSY) in a river basin (Celone, S-E Italy). The Soil and Water Assessment Tool model, calibrated with field observations, was used to evaluate runoff and SSY for the current land use (baseline) and six post-fire scenarios. From 1990 to 2011, at the basin scale, the average annual SSY was 5.60 t ha- 1yr−1 (SD = 3.47 t ha-1yr−1). 20% of the total drainage area showed a critical value of SSY (>10 t ha−1 yr−1). The effects of different fire-severity levels were predicted for one year after the fire, acting on a limited area (2.3% of the total basin area). At the basin scale, the post-fire effect on surface runoff was negligible for all scenarios (<0.4%), and the impact on SSY increased from 5.86 t ha−1 yr−1 up to 12.05 t ha−1 yr−1. At the subbasin scale, the post-fire logging scenario showed the highest increase of soil loss (SSY increased from 9.48 t ha−1 yr−1 to 57.40 t ha−1 yr−1). Post-fire mitigation treatments like straw mulching and erosion barriers effectively reduced soil erosion in high- and moderate-severity fires (19.12 t ha-1yr−1 and 20.93 t ha−1 yr−1, respectively). At the hydrological response unit level, the SSY estimated for the forest in the baseline ranged from 1.18 t ha- 1yr−1 to 2.04 t ha−1 yr−1. SSY increased more than one order of magnitude for the high-severity fire scenarios and ranged from 4.33 to 6.74 t ha−1 yr−1 in the very low-severity fire scenario, underlining the scale effect from the HRU to the basin scale.

Remote sensing inversion characteristic and driving factor analysis of wetland evapotranspiration in the Sanmenxia Reservoir area, China

Abstract Evapotranspiration in the hydrologic cycle realizes the energy and water transport in the atmosphere. Evapotranspiration differences concerning land-use types provide data for studying the evapotranspiration of river basins. To investigate the evapotranspiration in the reservoir under artificial regulation, we selected the river basin in the Sanmenxia Reservoir as the study area. Data sources are two-period Landsat8 OIL_TIRS remote sensing images during the growing season of wetland plants. Based on meteorological data in this river basin, we investigated the evapotranspiration differences of different land-use types using the Surface Energy Balance Algorithm for Land model. The FAO Penman–Monteith formula verified the remote sensing inversion results. Analysis shows that significant differences were manifested between wetland and non-wetland landscapes in evapotranspiration among different land-use types. Non-wetland landscapes accounted for about 97.23% of the river basin's total area, but their daily average evapotranspiration was only 7.26 mm/d. Those of wetland landscapes were 2.77% and 12.17 mm/d. In this river basin, the differences between the wetland and non-wetland landscapes in evapotranspiration are mainly associated with plant diversity, vegetation coverage and surface temperature (beyond other driving factors like meteorological and hydrological solar radiation factors).

Susceptibility assessment of debris flow from Baoxing River basin in Lushan earthquake zone, China

As one of the prevalent natural disasters, debris flow often occurs in mountainous areas and causes severe property losses. This study primarily focuses on describing the spatial distribution of debris flow in the Baoxing River basin in the Lushan earthquake zone, Sichuan Province, and then a susceptibility index map. Geographic information systems (GIS) and certainty factor (CF) method were used to establish the relationship between debris flow sub-basins and six predisposing parameters: elevation, slope angle, slope aspect, geologic periods, lithology, and NDVI (normalized difference vegetation index). The results show that elevations above 2400m, slopes from 20° to 45°, slope aspects of east, south-east, and south, geologic periods of Sinian, Ordovician, and Carboniferous, NDVIs of -1 to 0.2, lithology areas such as pyroclastic and carbonate of sedimentary rock, and metamorphic rock containing mafic and magnesian are the special conditions that cause debris flows. Furthermore, it has higher susceptibility potential for the combination of topography and geological parameters, including these predisposing parameters of elevation, slope angle, slope aspect, geologic periods, and lithology, than other combinations. The debris flow susceptibility assessment results show that the moderate and above susceptibility area accounts for around 94% of the total basin area or 51.5% of the study area; more than half of the study area is debris flow-prone, indicating that debris flows are quite active in the study area.