High Drainage Density Research Articles

Hydrological response-based watershed prioritization in semiarid, basaltic region of western India using frequency ratio, fuzzy logic and AHP method

Watersheds from semiarid regions are more sensitive to hydrological processes and sustainability of water resources than humid regions. Hence, it is indispensable to determine the response of watersheds to hydrological processes for water resource management. Thus, the hydrological response-based watershed prioritization study has been undertaken for eight sub-watersheds from semiarid, basaltic region of Western Ghats of India. Intent to this, a novel index has been parameterized using thematic layers such as drainage density, geology, soil, slope, landform classification, land use/land cover, rainfall and runoff (DGSLR). This study evaluates the performance of DGSLR index using three models, namely analytical hierarchy process (AHP), frequency ratio (FR) and fuzzy logic for sub-watershed-wise prioritization. The FR ratio showed the highest value for very high drainage density (8.73) indicating most probability for a high hydrological response. According to AHP weight, most influencing factors to hydrological processes are precipitation (25%), slope (19%) and land use/land cover (14%) followed by landform classification (11%). These three methods are prioritized study area into four classes, i.e., very high, high, moderate and low using area-weighted average method. These models showed that very high-priority area lies near the outlet of the watershed as well as the upper part of the watershed in high to very high priority in all three models. It covers 33.12% of the total area having a high average slope with high drainage density in sub-watersheds 1, 3, 7 and 8. The predictive capability of DGSLR index was computed by the area under the curve (AUC) and receiver operating characteristic (ROC) method, revealed average accuracy for FR method (AUC = 89%) better than AHP method (AUC = 77%) and fuzzy logic (AUC = 76%). This novel index could be used by the water resources researchers and planners in any terrain to understand the hydrological response.

Analyzing Factors of Groundwater Potential and Its Relation with Population in the Lower Barpani Watershed, Assam, India

The study explored potential of groundwater in the Lower Barpani watershed of Assam, India. Ten site-specific groundwater factors in the watershed were assigned weights through analytical hierarchy process. The weighted factors were integrated to prepare groundwater potential zones in GIS environment. Results revealed that the northern and northwestern parts of the study area have high groundwater potential. Gentle slope, flood plain, monsoon rainfall and location of numerous wetlands were found to be the major factors of high potential of groundwater in these parts. Medium groundwater potential was found in the southern part of the watershed. High drainage density but comparatively steeper slopes, nature of rocks and low water table have made this part of the watershed to have medium potential for groundwater. Low groundwater potential zone was identified mostly in the southwestern parts of the study area. Steep slope, high rate of runoff and low permeability due to hard rocks were found to be the main factors of low groundwater potential in these parts. Validation of groundwater potential zones with water yield revealed a strong positive relationship. Density of population and groundwater potential were positively correlated, and about 93% variation (r2 = 0.937) in density of population is explained by variation in groundwater potential. A linear correlation between groundwater zones and density of population suggests dependence of population on availability of groundwater. The methodology adopted in this study can be used for monitoring groundwater prospects for sustainable development and management of water resources in different geographical regions at various scales.

Flood Vulnerability Analysis Using Remote Sensing and GIS: A Case Study of Sidoarjo Regency

Sidoarjo Regency is one of the regencieslocatedin East Java Province Indonesia.Topography of some area in Sidoarjocan be categorized asin low altitude topography, so it makes this regency haspotential risk for flood disaster. Flood incident in Sidoarjo occurs almost every year. The cause of flooding in this district is an accumulation of several factors, such as heavy rainfall in the rainy season for every year, the low altitude areas in several sub-districts, land cover dominated roads and buildings in the some sub-districts, and the existence of several rivers flowing through the district. Application of Geographic Information System (GIS) and remote sensing is generated in this study to present information on the mapping of flood vulnerability zones in Sidoarjo. Integration of satellite and GIS datasets are carried out to prepare the flood zonation mapping of Sidoarjo Regency. Rainfall data fromTropical Rainfall Measuring Mission (TRMM), topographic map, land coverand the distance to main channel data are the datasetsused to identify the flood vulnerability. Flood vulnerability information includes the spatial distribution of flood hazard vulnerability in all sub-districs of Sidoarjo Regency. Spatial information is represented in the form of a map image. By knowing the spatial distribution, it can be known the level of vulnerability of areas to flooding. Most of Sidoarjo regency is flood vulnerable area, which is 76.24% or 658,702,719.91 sqm. It consist of 33.14% very high vulnerable area and 43.10% high vulnerable area. Very high vulnerable flood-prone areas in Sidoarjo Regency include most area of Jabon, Porong, Tanggulangin, Balongbendo, Krembung, Taman, and Waru sub-districts, while others are some parts of Candi, Sidoarjo, Buduran, and Gedangan sub-districts. High vulnerable flood-prone area include Tarik, Prambon, Tulangan, Wonoayu, and Sukodono sub-districts. The most dominant factors causing flooding in Sidoarjo Regency is the change of land cover, heavy rainfall, and high drainage density, while other factor also contributing to future flood vulnerability are land subsidence.

Exploring landslide susceptible zones by analytic hierarchy process (AHP) for the Gish River Basin, West Bengal, India

Landslide is a major threat in the Darjeeling Himalaya within sub-humid climate. Hence proper identification of landslide susceptible zone (LSZ) is very much essential. In this case a multi criterion evaluation approach is applied using thirteen selected indicators. The parameters are categorized into five categories viz. anthropogenic factor, surface causal factor, lithological causal factor, triggering factor and protective factor. Weighted composite model is prepared adopting weighting base as Analytic Hierarchy Process. The obtained result shows that near about 19.92 sq. km (approximately 7.52%) area within the basin is highly susceptible for landslides. High drainage density (avg. 4.31 km/sq. km), relatively steeper slope (>10°) accelerate this process. Beside the main landslide susceptibility layers five separate models of five causal factor groups are prepared and correlated with final LSZ for understanding the priority cluster. Lithological factors cluster appears as a dominant factor group (correlation value 0.95). This LSZ model is also validated by frequency as well as areal density of historical landslides. Beside this, the validation by ROC curve shows 84.00% area under the curve. So, the model can be treated as relevant.

Processes and Status of Land Degradation in a Plateau Fringe Region of Tropical Environment

The concept of land degradation means a temporary or permanent long-term decline in an ecosystem function and its productive capacity. Land degradation is the result of numerous factors or a combination thereof, including physical (climate change, soil degradation) as well as anthropogenic activities such as unsustainable land management practices. The present study primarily concerns the processes and status of land degradation in a part of the eastern Chotanagpur Plateau, India. The basin falls under the transitional zone, is undulating in nature and situated between the Chotanagpur Plateau area in the west and the greater Ganga plain area in the east. Largely, the basin falls under the Ganga River system. The major part of the population (>70%) of the area is dependent on agriculture which is largely affected by land degradation as well as soil erosion processes. The status of land degradation is estimated from different physical factors (geology, soil, geomorphology, slope, relief, groundwater, drainage density, rainfall intensity, green biomass cover) as well as anthropogenic factors (land use land cover change, population pressure on agricultural land, deforestation, irrigation intensity etc.). All these factors have been weighted with considerable importance to show the resultant varying intensities of land degradation. The different factor weighted raster has been multiplied in the GIS environment. The different vulnerable land degradation areas have been identified on the basis of the final weighted value. It has been shown that the upper reaches of the basin is considerably more prone to degradation due to its rugged topography, poor soil development and high drainage density. In the lower reaches of the Silabati River, the left bank is characterized by a high degreee of slope whereas the right bank shows intensive agricultural density, which couple up, to cause medium to high degree of land degradation vulnerability.

Developing water resources management strategies for South Sikkim District, India

Abstract This study was an effort to analyse the problems and prospects of water resource management and for suggesting strategies to meet the perceptive demand of 410 L of water per family during the winter period in South Sikkim district of Sikkim state, India. The district is of hilly terrain with an average rainfall of 1,500 mm per year, yet the district faces acute water shortage during the winter period. The hydro-geological and meteorological characteristics of the sub-watersheds were also studied. The district had very poor soil depth (<50 cm), low water holding capacity of soils (27–28%) with mostly sandy-loam texture. The sub-watersheds were found to have more than 70% first-order streams, higher bifurcation ratio (3.31), higher drainage density (3.99 km/km2) and higher stream density (8.65/km2). Sub-watersheds are mostly elongated with average form factors of 0.21. The rainfall pattern, soil type and morphometry of sub-watersheds indicated poor in situ moisture storage and limited possibility of stream water harvesting. To mitigate the scarcity of water in South Sikkim, the only option left for the planners is to promote household roof water harvesting so that water demand can be met during the average consecutive dry period of 30 days.

Watershed morphometric analysis of Wadi Baish Dam catchment area using integrated GIS-based approach

The integration of Remote Sensing (RS) and Geographic Information Systems (GIS) constitutes a powerful tool for the evaluation of watershed morphometric parameters. The benefits of this integration include saving time and effort as well as improving the accuracy of the analysis. Moreover, this technique is appropriate for describing the watershed and its streams. In this study, a detailed morphometric analysis of the Wadi Baish catchment area has been performed using the Shuttle Radar Topography Mission (SRTM). The performed morphometric analysis includes linear, areal, and relief aspects. The results of the morphometric analysis reveal that the catchment can be described as of eighth stream order and consists of an area of 4741.07 km2. Additionally, the basin is characterized by a relatively high mean value of bifurcation (4.012), indicative of the scarcity of permeable rocks with high slope in the area. This value of bifurcation ratio is consistent with the high drainage density value of 2.064 km/km2 and confirms the impermeability of the subsurface material and mountainous relief. The hypsometric integral of the catchment is 47.4%, and the erosion integral of the catchment is 52.6%, both were indications of a mature catchment area.

Hydrological investigations in the semi-arid Makhawan watershed, using morphometry

In order to understand the hydrological behavior of a catchment area, morphometric analysis of the drainage basin plays an important role to expresses the geology, geomorphology and structural antecedents. In the present study, morphometric analysis and its influence on hydrology were carried out in Makhawan watershed, Central India, using SRTM, remote sensing and GIS. SRTM data were used for preparation of DEM, slope and aspect maps. DEM was used to delineate the watershed limits and to extract the channel network, which was later updated using IRS 1D LISS III data. The hydrological module in ArcGIS was used for calculation of watershed and morphometric parameters, under linear, relief and aerial aspects. The watershed shows dendritic-to-sub-dendritic drainage pattern; however, parallel-to-sub-parallel pattern developed locally which may be due to rejuvenation of streams in mature stage with moderate drainage texture. High drainage density in the watershed is observed over impermeable subsurface material, sparse vegetation with high relief; whereas, low drainage density is found over permeable subsurface material and low relief. It has been found that low relief with low drainage density areas are favorable sites for more groundwater prospects.

Too much of a good thing? the role of detailed UAV imagery in characterizing large-scale badland drainage characteristics in South-Eastern Spain

ABSTRACTSome arid and semi-arid areas experience high erosion rates as a consequence of their geological and climatic conditions. This can lead to the development of badland environments characterized by very high drainage densities and the occurrence of a range of distinctive landforms indicative of fluvial dissection. These occur along a spectrum of scales and vary from small-scale arroyos or ramblas to large-scale rills and gullies. Drainage networks comprising the larger landforms can be easily identified using traditional remote-sensing methods, such as satellite or aerial imagery, and are therefore amenable to morphometric analyses. The smaller landforms however are not so easily detected. As a result, studies to date have been largely restricted to their direct field observation which is problematic due to their inherent inaccessibility, often on steep, unstable slopes. However, with the advent and popularization of unmanned aerial vehicles (UAVs), also known as drones, those landforms and geomorphological characteristics, which were once invisible to remotely-sensed aerial data can be incorporated into more detailed research. By using one of the most extensively studied badland locations in Europe – the Tabernas Desert in South-Eastern Spain – this article describes the characterization of a large-scale drainage basin (294 m2) using high definition orthophotography and digital elevation model collected from an unmanned rotorcraft and processed using structure from motion software. Results provide an extremely detailed three-dimensional (3D) reconstruction of the study site, and solve one of the inherent issues working with such large scales, namely the significant difference between 2D and 3D measurements. The article concludes by comparing the results obtained with the UAV with those obtained using existing remotely-sensed imagery and by exploring the challenges experienced when working with bespoke high-resolution aerial imagery, such as when too much detail becomes an issue, and the role of this increasing resolution of observation in geomorphological and hydrological analysis.

Influence of structures on drainage patterns in the Tushka region, SW Egypt

Remote sensing (radar, thermal and topographic) and geophysical (Vertical Electrical Sounding and Ground Penetrating Radar) data are used to understand areas with enhanced groundwater potential in deeper aquifer settings between 22°0′–22°56′N and 30°21–31°20′E in the Tushka area of southwest Egypt. The premise is that areas with enhanced groundwater accumulations represent the best locations for agricultural development that is underway in this region and that deeper sources groundwater resources are the most sustainable. New fluvial and structural interpretations emphasize that the desert landscape was produced by fluvial action in the past. The correlation of high drainage and fault densities, coincident with gentle slope, guided sites for geophysical investigation that provides information about the aquifer depth and distribution, and the subsurface distribution of faults. Results confirm the presence of subsurface fault plains and fault zones and potential water aquifers at these locations. Surface environments further demonstrated an abundance of shrubs and cultivatable soils. The new approach therefore is a cost effective and noninvasive technique that can be applied throughout the eastern Sahara to assist in resource management decisions and support the planned agricultural expansion.

Constraining the annual groundwater contribution to the water balance of an agricultural floodplain using radon: The importance of floods

AbstractThe water balance of drained floodplains is highly dynamic with complex groundwater–surface water interactions operating over varying spatial and temporal scales. Here we hypothesize that the majority of groundwater discharge will follow flood events in a modified wetland. To test this hypothesis, we developed a detailed water balance that quantifies the contribution of groundwater discharge to the annual water budget of an extensively drained agricultural floodplain. A clear relationship between surface water radon measurements and groundwater level indicated alternating connection–disconnection dynamics between the drains and shallow groundwater. This relationship was used to develop a radon mass balance to quantitatively model groundwater discharge continuously throughout the year. Groundwater discharge varied by four orders of magnitude over the study period, with daily average rates ranging from 0 to 27,200 m3 d−1, peaking just a few hours after floods receded. Flood events occurred only 12% of the time yet contributed 72–76% of the total groundwater discharge. During flood recession periods, aerial groundwater discharge rates reached up to 325 cm d−1 which were some of the highest rates ever estimated. We proposed that the high drainage density of this site (12.4 km constructed drains km−2 catchment area) enhanced groundwater discharge during wet periods due to increased connectivity with the soil. Overall, groundwater discharge contributed 30–80% to the total surface water discharge. This study offers insight into the dynamic behavior of groundwater within an extensively drained floodplain, and the importance of capturing flood events to quantify total groundwater contribution to floodplain water balances.

Evaluation of different digital elevation models for analyzing drainage morphometric parameters in a mountainous terrain: a case study of the Supin-Upper Tons Basin, Indian Himalayas.

Background With myriad geospatial datasets now available for terrain information extraction and particularly streamline demarcation, there arises questions regarding the scale, accuracy and sensitivity of the initial dataset from which these aspects are derived, as they influence all other parameters computed subsequently. In this study, digital elevation models (DEM) derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER V2), Shuttle Radar Topography Mission (SRTM V4, C-Band, 3 arc-second), Cartosat -1 (CartoDEM 1.0) and topographical maps (R.F. 1:250,000 and 1:50,000), have been used to individually extract and analyze the relief, surface, size, shape and texture properties of a mountainous drainage basin.ResultsNestled inside a mountainous setting, the basin is a semi-elongated one with high relief ratio (>90), steep slopes (25°–30°) and high drainage density (>3.5 km/sq km), as computed from the different DEMs. The basin terrain and stream network is extracted from each DEM, whose morphometric attributes are compared with the surveyed stream networks present in the topographical maps, with resampling of finer DEM datasets to coarser resolutions, to reduce scale-implications during the delineation process. Ground truth verifications for altitudinal accuracy have also been done by a GPS survey.ConclusionsDEMs derived from the 1:50,000 topographical map and ASTER GDEM V2 data are found to be more accurate and consistent in terms of absolute accuracy, than the other generated or available DEM data products, on basis of the morphometric parameters extracted from each. They also exhibit a certain degree of proximity to the surveyed topographical map.

Evaluation of groundwater potential using geospatial techniques

The issue of unsustainable groundwater utilization is becoming increasingly an evident problem and the key concern for many developing countries. One of the problems is the absence of updated spatial information on the quantity and distribution of groundwater resource. Like the other developing countries, groundwater evaluation in Ethiopia has been usually conducted using field survey which is not feasible in terms of time and resource. This study was conducted in Northern Ethiopia, Wollo Zone, in Gerardo River Catchment district to spatially delineate the groundwater potential areas using geospatial and MCDA tools. To do so, eight major biophysical and environmental factors like geomorphology, lithology, slope, rainfall, land use land cover (LULC), soil, lineament density and drainage density were considered. The sources of these data were satellite image, digital elevation model (DEM), existing thematic maps and metrological station data. Landsat image was used in ERDAS Imagine to drive the LULC of the area, while the geomorphology, soil, and lithology of the area were identified and classified through field survey and digitized from existing maps using the ArcGIS software. The slope, lineament and drainage density of the area were derived from DEM using spatial analysis tools. The rainfall surface map was generated using the thissen polygon interpolation. Finally, after all these thematic maps were organized, weighted value determination for each factor and its field value was computed using IDRSI software. At last, all the factors were integrated together and computed the model using the weighted overlay so that potential groundwater areas were mapped. The findings depicted that the most potential groundwater areas are found in the central and eastern parts of the study area, while the northern and western parts of the Gerado River Catchment have poor potential of groundwater availability. This is mainly due to the cumulative effect of steep topographic and high drainage density. At last, once the potential groundwater areas were identified, cross validation of the resultant model was carefully carried out using existing data of dung wells and bore holes. The point data of dung wells and bore holes were overlaid on groundwater potential suitability map and coincide with the expected values. Generally, from this study, it can be concluded that RS and GIS with the help of MCDA are important tools in monitoring and evaluation of groundwater resource potential areas.

Caracterização morfométrica das sub-bacias no município de Xapuri: subsídios à gestão territorial na Amazônia Ocidental

This work morphometrically characterized watersheds that occur in the municipality of Xapuri and constructed a model that explains the extent of watershed impact and resilience. Emphasis was given to provide a decision-making tool for non-specialists. The study area is located in the State of Acre and has four sub-basins: Alto Acre, Rio Xapuri, Xipamanu and Riozinho do Rola. A cartographic survey was conducted, to include the morphometric characteristics of the area and land use and cover features that resulted in the soil-hydrographic zoning of the municipality. Sub-basins Xapuri, Xipamanu and Riozinho do Rola revealed drainage densities and orders that indicate low drainage efficiency, while Alto Acre presented high drainage orders (ninth order) and densities, contrary the geometric indices and drainage densities, and is considered to have efficient drainage. Considerable alterations in permanent preservation areas occur in the municipality of Xapuri, with conversion to less resilient areas highly sensitive to impacts. The soil-hydrographic zoning assists in visualizing the municipality in a land management context through an ecosystem approach and a qualitative view of the possibilities and weaknesses.

Hydrogeomorphological Study for Shallow Groundwater Prospecting Within Solani Watershed in Haridwar District, Uttranchal. India

Hydrogeomorphological study has been carried out to demarcate shallow groundwater prospecting zones of the Solani watershed in Haridwar district, Uttranchal, India. An integrated geographic database, consisting of spatial and non spatial data, has been generated for the study area using remote sensing and geographical information system (GIS) technique coupled with ground truth investigations. The spatial database layers like hydrogeomorphology, land use/land cover, soil, slope and geology generated from topographic maps and satellite data while the non spatial data is derived primarily from ground checking during field survey and from the available literature. These data have been stored in the GIS databank for digitization, computational purpose and output generation to locate the availability of shallow groundwater in solani watershed for prospecting purposes. The result had been show that the southern part of solani watershed associated with hydrogeomorphological unit of lower piedmont (covering 367 km2) has very good to excellent categories of prospect zones while the shallow groundwater prospect zones is very poor in the northern part (hilly area) covering about 163km2of the study due to steeply slopes and very high drainage densities which are grouped together as runoff zone in the study area. In the middle part associated with upper piedmont zone, the category of prospecting shallow groundwater is good and covering about 96 km2 of the area with gentle slope and low drainage density. The present study shows that a spatial technique has been proved to be very efficient in delineation of groundwater prospect zone of the considered area.

Influência das características morfométricas da bacia hidrográfica do rio Benevente nas enchentes no município de Alfredo Chaves-ES

Floods affect the lives of thousands of people around the world and their causes may be related to both natural and anthropogenic factors. The objective of this study was to evaluate the relationship between the Benevente River watershed morphometry and the occurrence of floods in the town of Alfredo Chaves, Espirito Santo State, Brazil. The database consisted of a digital elevation model (ASTER), a vector hydrographic network of IBGE and a 40-year period series of daily precipitation. The morphometric parameters were obtained using Geographic Information Systems (GIS). The study area has an elongated shape, with a high drainage density, strongly undulate topography and an average slope of 42.75%. The altitude ranged from 480 to 1591 m. November, December and January were the wettest months, with a monthly average rainfall of 246.7, 261.5 and 204.2 mm, respectively. It was concluded that high slopes of the basin and of the main river, coupled with increased use and occupation of the land, exerts significant influence on the runoff in the basin, increasing the chances of the occurrence of flood peaks.

Spatial and Temporal Variation of Groundwater Level and its Relation to Drainage and Intrusive Rocks in a part of Nalgonda District, Andhra Pradesh, India

Drainage and lineaments play an important role in the flow of groundwater. The objective of this study is to assess the groundwater level and its relation to drainage and lineaments in a hard rock region of a part of Nalgonda district, Andhra Pradesh, southern India. The region predominantly comprise of granites and gneisses. Groundwater level was measured in 42 representative wells in this study area from March 2008 to January 2010 once in every two months. Observed groundwater levels were compared with drainage and dyke density. Groundwater level fluctuation in low drainage density region is generally greater than those in moderate and high drainage density regions. The dykes do not act as barriers for groundwater flow as they are highly weathered. The quantity and flow of groundwater in this region is predominantly controlled by drainage density, intensity of weathering and presence of fractures. Thus the study indicate that the drainage density play a major role in groundwater level fluctuation and as the dykes are weathered, they do not affect the groundwater flow in this shallow unconfined aquifer.

Geomorphometric analysis of a hilly watershed in north east India

Morphometric analysis of a hilly watershed was carried out using GIS. The drainage map generated from the Survey of India toposheets was used for morphometric analysis of the watershed in terms of stream order, stream length, bifurcation ratio, relief ratio, drainage density, stream frequency, drainage texture, form factor, circulatory ratio, elongation ratio, infiltration number and ruggedness number. The Um Shipra watershed is a fifth order watershed having dendritic drainage pattern with high drainage density (6.22 km.km−2). The logarithmic plot of the stream length versus stream order showed a linear relationship indicating the watershed has developed over a homogeneous rock material. The mean bifurcation ratio of 1.71 indicated absence of strong structural control on the drainage pattern and that the watershed was structurally less disturbed. The number of streams belonging to the order I, II, III, IV and V were found to be 327, 147, 78, 45 and 46 respectively. Lower values of form factor (0.19), circularity ratio (0.29) and elongation ratio (0.49) suggested that the watershed has elongated shape with lower peak flows for longer duration. The ruggedness number having relatively higher value implied that the area has rugged topography which is prone to soil erosion. Higher values of stream frequency and drainage density indicated that the watershed has high runoff potential despite having lower peak flow creating a good scope for surface water resource development. The results obtained can serve as a useful input for developing soil and water resources conservation and management plan on a watershed basis.

Spatial decision support system for assessing lake pollution hazard: southeastern pampean shallow lakes (Argentina) as a case study

This study gives an account of the implementation of a decision support system as a logical framework for assessing lake pollution hazard. The use of this system is demonstrated with an example from two lake watersheds, each one with different land-use, soil and topographic characteristics and also management regulations for natural resource protection. Lake pollution hazard is assessed as a function of two primary topics: hydrologic and soil conditions. This model shows the state of each evaluated subwatershed with respect to its potential contribution to lake pollution hazard based mainly on easily measurable and commonly used parameters: drainage density, hydraulic gradient, water table depth, soil media, land-cover and topography. Mapped outputs from the logic model allowed the identification of several subwatersheds in each lake system as the main water resource protection areas. La Brava Lake Watershed results reasonably fit the natural conditions of the watershed, identifying those subwatersheds with a moderate to high drainage density, high hydraulic gradient and extensive agricultural activities. Regarding Los Padres Lake Watershed, moderate to high drainage density, a high to a very high hydraulic gradient, shallow water depth, silt-loam soil texture and intensive agricultural and residential lands, contributed to a high lake pollution hazard. Results highlighted differences between both freshwater systems, being Los Padres Lake Watershed a more vulnerable ecosystem, requiring decision maker’s intervention based on accurate and up-to-date information.

An unnamed fluvial valley system formed under different climates at Xanthe Terra, Mars

Analyzing an unnamed fluvial system (at 5.2N 301.4E) in Xanthe Terra on Mars for the first time, the following chronology could be reconstructed. The first period of the fluvial erosion of the area produced channels with higher drainage density than later events, but some resurfacing after this period erased these early, probably interconnected tributary systems and left behind only separate channel sections with eroded appearance. In the second period of fluvial erosion three deep and obvious channels were formed. In a third period, the main inlet to the terminal crater was eroded even more heavily. The last two episodes produced two different, characteristic cross sectional and longitudinal profiles: (1) narrow, shallow and nearly straight profiles, and (2) a wider, deeper and somewhat convex shaped profile. These two profile shapes resemble to other fluvial systems’ in the Xanthe Terra region. The existence of these two different types of channel morphology suggests the change in the erosional process could be at least regional and probably related to the change of fluvial erosion’s style on Mars forced by climatic changes.