Impact of Kiri dam on the lower reaches of river Gongola, Nigeria

Changes in Geomorphic characteristics in the lower reaches of the Gongola River channel following construction of Kiri dam have been investigated. The study focused on changes in the channel bankfull width and of riverbed width after the control of the river flow, variation in discharge characteristics between pre- and post- dam periods and the impact of discharge variation on post- dam river channel. Results of the analysis revealed that the main effect of the impoundment of the Gongola channel is a drastic decrease in flood peaks below the reservoir by 11.5% (from 1,420 m³/sec to 1,256 m³/sec). The low flows have on the other hand increased by 268% (from 5.7 m³/sec to 21 m³/sec). The resultant effect of decrease in the discharge was reduction in the channel bankfull and riverbed widths by 38.3% and 72.2% respectively. Also, the post- dam channel became less sinuous and braided in some of the reaches downstream. Discharges of high peaks were found during the period of maximum precipitation (June to September) whereas low discharges were recorded during the period of minimum or no precipitation (December to May). Some of the observed implications of the flow control on the geometric variables were reduction in the overall channel width, concave bank erosion and emergence of vegetation in some of the reaches.     

Study of cloudburst and flash floods around Leh, India, during August 4–6, 2010

Leh and surrounding region of the Ladakh mountain range in the trans-Himalaya experienced multiple cloudbursts and associated flash floods during August 4–6, 2010. However, 12.8 mm/day rainfall recorded at the nearest meteorological station at Leh did not corroborate with the flood severity. For better understanding of this event, hydrological analysis and atmospheric modeling are carried out in tandem. Two small catchments (<3 km²) were studied along the stream continuum to assess the flood characteristics to identify the cloudburst impact zones. Peak flood discharges were estimated close to the head wall region and at the catchment outlet of the Leh town and the Sabu eastern tributary catchments. Storm runoff depth is estimated by developing a triangular hydrograph by using the known time base of the flood hydrograph. This triangular hydrographs have been transformed further into storm hydrographs to gain a better understanding of the storm duration by using the dimensionless hydrograph method at selected cross sections. Storm duration is estimated by using the relationship between time to peak and time of concentration of the catchment. The peak flood estimates ranged from 122(±35 %) m³/s for Leh town catchment (2.393 km²), 545(±35 %) m³/s for Sabu eastern tributary catchment (2.831 km²) to 1,070(±35 %) m³/sec for Sabu catchment (64.95 km²). To assess the atmospheric processes associated with this event, a triple nest simulation (27, 9 and 3 km) is performed using Advanced Research Weather Research and Forecasting (WRF) modeling system. The simulation does show the evolution of the event from August 4 to 6, 2010. Observation constraints, orographic responses, etc. make such analysis complex at such scale. Independent estimate by the atmospheric process model and the hydrological method shows the storm depth of 70 mm and 91.8(±35 %) mm, respectively, in catchment scale. Hydrological evaluation further refined the spatial and temporal extents of the cloudbursts in the respective catchments with an estimated storm depth of 209(±35 %) mm in 11.9 min and 320(±35 %) in 8.8 min occurring in an area of 0.842–1.601 km², respectively. This study shows that the insight developed on the cloudburst phenomena by the atmospheric and the hydrological modeling is hugely constrained by the spatial and temporal scales of data used for the analysis. Apart from this, study also highlighted the regular occurrence of cloudburst events over this region in the recent past. Most of such events go unreported due to lack of monitoring mechanisms in the region and weaken our ability to understand these events in complete perspective.     

Lithology, landscape dissection and glaciation controls on catchment erosion as determined by cosmogenic nuclides in river sediment (the Wutach Gorge, Black Forest)

Cosmogenic nuclides, measured in quartz from recent river bedload, provide a novel tool to quantify catchment‐wide erosion rates at geologically meaningful time scales. Here we present an analysis of the geomorphological evolution of the 350 km² Wutach catchment in the uplands of the south‐west German Black Forest. The robustness of the method is demonstrated by the fact that, although the area was affected by river capture at 18 kyr bp , the formed gorge is so narrow that spatially averaged erosion rates were not resolvably perturbed. However, because cosmogenic nuclides preserve an erosion memory of several thousand years, the only perturbation introduced was detected in the minor areas that have been subject to the last maximum glaciation. In unglaciated areas, an important relationship between lithology and erosion can by quantified: sandstone lithologies erode at 12–18 mm kyr^?1, granite lithologies at 35–47 mm kyr^?1 and limestone lithologies (as deduced from river load gauging) at 70–90 mm kyr^?1.     

Comparison of volumetric and remote sensing methods (TLS) for assessing the development of a permanent forested loess gully

The gully systems develop a compact network dissecting the loess cover of the NW part of the Lublin Upland. They are overgrown by dense and multi-storey forest assemblages. It is very difficult to apply teledetection techniques, GPS positioning, and geodesic tools, such as a laser rangefinder or total station, for monitoring of gully development. The detailed research, involving the comparison of traditional and modern methods, was conducted in a gully with a secondary erosional dissection, developing in the gully bottom with varied intensity for the last 15 years. In the period of comparative research (2012/2013), the rate of development of the erosional dissection was measured by means of traditional methods as well as a Leica HDS 7000 laser scanner. 3D laser scanning permitted precise terrain modelling and the assessment of qualitative and quantitative spatial changes. This paper compares the results of three measurement campaigns. The analysis showed intensive development of the dissection, manifested in an increase in its volume (37 %), retreat of the erosion scarp (32 m), deep erosion (19 %), and lateral erosion (27 %). Registered moderate snowmelt in 2013 caused the volume dissection to increase by 57 m³, mainly as a result of the gully bottom scouring. During heavy rainfalls in June, the landforms were widened by a further 217 m³ and observed deepening and widening of erosive potholes. The prevalence of deep erosion resulted in the transformation back into a V-shaped cross section. A total of 37.3 Mg km⁻² of material was discharged from the gully catchment during snowmelt runoffs in 2013. A precipitation event in June 2013 caused the discharge of 856.9 Mg km⁻² of material from the catchment. The obtained results confirm that snowmelt erosion determines the spatial development of perennial gullies, but the volume of material discharged from the catchment depends on the occurrence of extreme precipitation during the warm season.

     

Assessing the impacts of changing land cover and climate on Hokersar wetland in Indian Himalayas

Monitoring the spatiotemporal changes in wetlands and assessing their causal factors is critical for developing robust strategies for the conservation and restoration of these ecologically important ecosystems. In this study, the spatiotemporal changes in the land cover system within a Himalayan wetland and its catchment were assessed and correlated using a time series of satellite, historical, and field data. Significant changes in the spatial extent, water depth, and the land system of the Hokersar wetland were observed from the spatiotemporal analysis of the data from 1969 to 2008. The wetland area has shrunk from 18.75 km² in 1969 to 13 km² in 2008 with drastic reduction in the water depth of the wetland. The marshy lands, habitat of the migratory birds, have shrunk from 16.3 km² in 1969 to 5.62 km² in 2008 and have been colonized by various other land cover types. The land system and water extent changes within the wetland were related to the spatiotemporal changes in the land cover and hydrometeorological variables at the catchment scale. Significant changes in the forest cover (88.33–55.78 km²), settlement (4.63–15.35 km²), and water bodies (1.75–0.51 km²) were observed in the catchment. It is concluded that the urbanization, deforestation, changes in the hydrologic and climatic conditions, and other land system changes observed in the catchment are the main causes responsible for the depleting wetland extent, water depth, and biodiversity by adversely influencing the hydrologic erosion and other land surface processes in the catchment. All these causes and effects are manifest in the form of deterioration of the water quality, water quantity, the biodiversity changes, and the decreasing migratory bird population in the wetland.     

Short‐time (<10 ka) denudation rates as a marker of active folding in the Zagros Fold Belt (Iran)

Coupling between tectonics and surface processes is usually ill‐quantified as other factors such as climate and lithology affect the later. We provide catchment‐wide ¹⁰Be denudation rates of the Mand catchment in the Zagros Fold Belt (Iran) to infer correlations between these rates and ongoing tectonic shortening in the region. Denudation rates are generally low (~0.05–0.1 mm/a) but increase to ~1 mm/a near the Halikan anticline, where changes in precipitation, lithology or hillslope gradient are insignificant. The denudation rates upstream and downstream of the Halikan anticline are consistent with the GPS convergence rates in these areas. The sharp increase in denudation rates over the Halikan anticline denotes its growth as previously detected from terrace incision. It also reveals small wavelength coupling between crustal deformation and erosion. Denudation rates are therefore a useful and sensitive tool that helps constraining non‐brittle active tectonics such as folding of a sedimentary cover.     

Sedimentary architecture and genesis of Holocene shallow-water mud-mounds, northern Belize

Abstract Cangrejo and Bulkhead Shoals are areally extensive, Holocene biodetrital mud‐mounds in northern Belize. They encompass areas of 20 km² and 35 km² in distal and proximal positions, respectively, on a wide and shallow‐water, microtidal carbonate shelf where storms are the major process affecting sediment dynamics. Sediments at each mound are primarily biodetrital and comprise part of a eustatically forced, dominantly subtidal cycle with a recognizable deepening‐upward transgressive systems tract, condensed section and shallowing‐upward highstand systems tract. Antecedent topographic relief on Pleistocene limestone bedrock also provided marine accommodation space for deposition of sediments that are a maximum of 7·6 m thick at Cangrejo and 4·5 m thick at Bulkhead. Despite differences in energy levels and location, facies and internal sedimentological architectures of the mud‐mounds are similar. On top of Pleistocene limestone or buried soil developed on it are mangrove peat and overlying to laterally correlative shelly gravels. Deposition of these basal transgressive, premound facies tracked the rapid rate of sea‐level rise from about 6400–6500 years BP to 4500 years BP, and the thin basal sedimentation unit of the overlying mound‐core appears to be a condensed section. Following this, the thick and complex facies mosaic comprising mound‐cores represents highstand systems tract sediments deposited in the last ≈ 4500 years during slow and decelerating sea‐level rise. Within these sections, there is an early phase of progradationally offlapping catch‐up deposition and a later (and current) phase of aggradational keep‐up deposition. The mound‐cores comprise stacked storm‐deposited autogenic sedimentation units, the upper bounding surfaces of which are mostly eroded former sediment–water interfaces below which depositional textures have largely been overprinted by biogenic processes associated with Thalassia‐colonized surfaces. Vertical stacking of these units imparts a quasi‐cyclic architecture to the section that superficially mimics metre‐scale parasequences in ancient rocks. The locations of the mud‐mounds and the tidal channels transecting them have apparently been stable over the last 50 years. Characteristics that might distinguish these mud‐mounds and those mudbanks deposited in more restricted settings such as Florida Bay are their broad areal extent, high proportion of sand‐size sediment fractions and relatively abundant biotic particles derived from adjoining open shelf areas.     

Electrical resistivity surveys to delineate groundwater potential aquifers in Peddavanka watershed,Anantapur District,Andhra Pradesh,India

Vertical electrical resistivity soundings were conducted in order to delineate groundwater potential aquifers in Peddavanka watershed, which is a catchment of about 398 km² in Anantapur District, Andhra Pradesh, India. The main lithologic units in the watershed are quartzite, limestone, shale, and alluvium. Ninety-nine vertical electrical soundings were conducted using the Schlumberger configuration, covering the entire watershed. The data were interpreted with the help of master curves and auxiliary point charts. Interpretations of VES were used to generate a top layer apparent resistivity contour map and longitudinal conductance map. Isoresistivity contour maps were prepared and interpreted in terms of resistivity and thickness of various sub-surface layers using computer software (SURFER), and isocontour diagrams depicting the depth to bedrock were prepared. Resistivity results were correlated with the existing lithology. Based on the depth to bedrock, the thickness of the saturated layer and the resistivity of the second layer, a groundwater potential map has been prepared, in which good, moderate, and poor zones are classified. The study reveals that the weathered and fractured portions in shale and limestone that occur in the southernmost and central portions of the watershed area constitute the productive water-bearing zones categorized as good groundwater potential aquifers.     

Source of the River Shannon,Ireland

The Shannon is the longest river in the British Isles (280 km) and drains an area of about 15,530 km². The source of the river is Shannon Pot, a karst rising in County Cavan, which is one of the most famous springs in Ireland. Water tracer experiments have shown that the rising drains an immediate area of about 12.8 km² on the slopes of Cuilcagh Mountain, of which about 60% is underlain by limestone. However, two sinks 10–11 km east of the rising and ca. 200 m higher have also been shown to be hydrologically connected during high flow conditions. This suggests that Shannon Pot may once have had a substantially larger catchment area.     

Recent sediment flux and erosional processes in a Welsh upland lake-catchment based on magnetic susceptibility measurements

Single sample magnetic susceptibility measurements are used to correlate synchronous levels in 16 cores of dated (²¹⁰Pb, ¹³⁷Cs) recent sediment taken from the deep and oligotrophic Llyn Peris, N. Wales, in order to provide a basis for calculating total sediment and chemical influx through time. Results show that sediment influx has steadily increased since c. 1750 A.D. to reach peak levels in the period 1966–1976 A.D., equivalent to a rise in erosion in the catchment from c. 5 t km⁻² yr⁻¹ to c. 42 t km⁻² yr⁻¹. Comparison of down-core susceptibility fluctuations with sediment pollen and organic pigment data indicates that maximum susceptibility values relate to periods of channel erosion and minimum susceptibility values relate to periods of slate debris inwash from spoil tips in the catchment. A study of historical records reveals that pre-twentieth-century peak levels of erosion were due to the effects of extractive industries, while twentieth-century erosion has been caused by overgrazing, increased trampling pressure, and heavy construction works in the catchment.     

Modeling runoff and soil erosion in a catchment area, using the GIS, in the Himalayan region, India

Remote sensing data and GIS techniques have been used to compute runoff and soil erosion in the catchment area along the NH-1A between Udhampur and Kud covering an area of approximately 181 km². Different thematic layers, for example lithology, a landuse and landcover map, geomorphology, a slope map, and a soil-texture map, were generated from these input data. By use of the US Soil Conservation Service curve number method, estimated runoff potential was classified into five levels—very low, low, moderate, high, and very high. Data integration was performed by use of the weighting rating technique, a conventional qualitative method, to give a runoff potential index value. The runoff potential index values were used to delineate the runoff potential zones, namely low, moderate, high, and very high. Annual spatial soil loss estimation was computed using the Morgan–Morgan–Finney mathematical model in conjunction with remote sensing data and GIS techniques. Greater soil erosion was found to occur in the northwestern part of the catchment area. When average soil loss from the catchment area was calculated it was found that a maximum average soil loss of more than 20 t ha⁻¹ occurred in 31 km² of the catchment area.     

Late Quaternary megafloods from Glacial Lake Atna, Southcentral Alaska, U.S.A.

Geomorphic, stratigraphic, geotechnical, and biogeographic evidence indicate that failure of a Pleistocene ice dam between 15.5 and 26 ka generated a megaflood from Glacial Lake Atna down the Matanuska Valley. While it has long been recognized that Lake Atna occupied ≥ 9000 km² of south-central Alaska's Copper River Basin, little attention has focused on the lake's discharge locations and behaviors. Digital elevation model and geomorphic analyses suggest that progressive lowering of the lake level by decanting over spillways exposed during glacial retreat led to sequential discharges down the Matanuska, Susitna, Tok, and Copper river valleys. Lake Atna's size, ∼ 50 ka duration, and sequential connection to four major drainages likely made it a regionally important late Pleistocene freshwater refugium. We estimate a catastrophic Matanuska megaflood would have released 500–1400 km³ at a maximum rate of ≥ 3 × 10⁶ m³ s^{− 1}. Volumes for the other outlets ranged from 200 to 2600 km³ and estimated maximum discharges ranged from 0.8 to 11.3 × 10⁶ m³ s^{− 1}, making Lake Atna a serial generator of some of the largest known freshwater megafloods.     

Threat of glacial lake outburst flood to Tehsil Gupis from Khukush Lake, District Ghizer, Gilgit Baltistan, Pakistan

Glacial lake outburst flood (GLOF) is a powerful natural phenomenon that is very active in the Karakoram and Himalayas. This paper presents a case study from Gupis Tehsil in northern areas of Pakistan that is exposed to GLOFs from nine different glacial lakes in its upper catchment areas. Khukush Lake being the largest of all the glacial lakes has been studied and a flood attenuation model has been created for the whole Gupis Tehsil. This lake covers almost 2.2 km² of surface area, and its calculated volume is 2.6 × 10⁴ m³. In case of its outburst, the peak flow discharge is calculated to be 7,642 m³/s. The catchment area which contributes water and debris to the lake is 170 km². This lake is dammed by a glacial moraine, which is not strong enough to sustain the pressure for a longer period of time. Other factors that are reducing the reliability of the dam are the secondary hazards which are in direct contact with the lake, and in case of their reactivation, they can put severe impacts on the dam. There are eight potential sites of the snow avalanche activity where debris along with snow may fall directly into the lake producing a strong wave. This strong wave of water will increase the pressure on the dam and ultimately will increase the probability for its outburst. The presense of water springs towards the downstream side of the natural dam also indicate the presence of hidden channels passing through the dam which may weaken the shear strength of the dam. Almost 24 villages settled along either sides of the Gupis River are critically studied for the expected flood from Khukush Lake. With few exceptions, almost 20–25 % area of all the villages will be affected from this flood.     

A Late Quaternary catastrophic flood in the Lahul Himalayas

Impressive flood deposits are described resulting from a catastrophic lake outburst in the Upper Chandra valley in the Lahul Himalaya, northern India. Reconstructions of the former glacial lake, Glacial Lake Batal, and the discharges were undertaken using landforms and sediment data. The glacial dam burst released 1.496 km³ of water in 0.72 days, with peak discharges of between 21000 and 27000 m³ s⁻¹ at Batal. Dating by OSL suggests the flood occurred ca. 36.9 ± 8.4 to 43.4 ± 10.3 ka ago. This cataclysmic flood was responsible for major resedimentation and landscape modification within the Chandra valley.     

Carbonate and silicate weathering in two presently glaciated, crystalline catchments in the Swiss Alps

We present a weathering mass balance of the presently glaciated Rhône and Oberaar catchments, located within the crystalline Aar massif (central Switzerland). Annual chemical and physical weathering fluxes are calculated from the monthly weighted means of meltwater samples taken from July, 1999 to May, 2001 and are corrected for precipitation inputs. The meltwater composition issuing from the Oberaar and Rhône catchments is dominated by calcium, which represents 81% and 55% of the total cation flux respectively (i.e. 555 and 82-96 keq km⁻² yr⁻¹). The six to seven times higher Ca²⁺ denudation flux from the Oberaar catchment is attributed to the presence of a strongly foliated gneissic zone. The gneissic zone has an elevated calcite content (as reflected by the 4.6 times higher calcite content of the suspended sediments from Oberaar compared to Rhône) and a higher mechanical erosion rate (resulting in a higher flux of suspended sediment). The mean flux of suspended calcite of the Oberaar meltwaters during the ablation period is 7 times greater than that of the Rhône meltwaters. Taking the suspended calcite as a proxy for the total (including sub-glacial sediments) weathering calcite surface area, it appears that the available surface area is an important factor in controlling weathering rates. However, we also observe an increased supply of protons for carbonate dissolution in the Oberaar catchment, where the sulphate denudation flux is six times greater. Carbonic acid is the second important source of protons, and we calculate that three times as much atmospheric CO₂ is drawn down (short term) in the Oberaar catchment. Silica fluxes from the two catchments are comparable with each other, but are 100 kmol km² yr⁻¹ lower than fluxes from physically comparable, non-glaciated basins.     

湘西-黔东下寒武统清虚洞组藻灰岩沉积特征及其找矿意义

铅锌矿是湘西-黔东地区的优势矿种,资源丰富,开发历史悠久,找矿潜力巨大。综合分析前人有关湘西-黔东生物礁的资料,介绍了藻灰岩的沉积特征,并结合大量实际地质资料,对藻灰岩控矿进行了论述。结果表明: 成矿物质主要来源于藻类及碳酸盐泥对Pb²⁺、Zn²⁺离子的吸取,矿床成因属于沉积成岩矿床类型,兼有成岩期后矿床性质; 藻礁灰岩与不同岩性的接合部位及其附近等微地球化学障区,往往就是铅锌富矿体产出部位; 藻礁灰岩与礁间通道的薄层泥质白云质灰岩呈指状交叉接触处,也常有铅锌富矿体产出; 铅锌富矿体基本上产于清虚洞组灰岩段中,且明显受该段藻礁灰岩控制。为满足国内外对铅锌矿日益增长的消费需要,深入研究区内铅锌矿的地层岩相岩石控矿因素及其富集规律,指导该地区藻灰岩中铅锌矿找矿工作,具有重要的现实意义。     

Analysis of low-flow characteristics for catchments in Dongjiang Basin, China

Low-flow indices have been determined from long-term daily streamflow data for 13 catchments in Dongjiang Basin in southern China. The Brutsaert-Nieber method was applied to estimate catchment-scale effective groundwater parameters; representative values were 4.5?×?10^?4 m² s^?1 for the hydraulic diffusivity; 3.19?×?10^?5 m² s^?1/2 for the hydraulic desorptivity; 2.27?×?10^?4 m s^?1 for the hydraulic conductivity; and 0.2617 for the drainable porosity. The response constants correlate well with the total stream length and catchment area. Solutions of the linearised Boussinesq equation were used to guide the development of regional multivariate regression models for estimating low-flow indices from the catchment-scale effective parameters. Results showed that these catchments exhibit similar low-flow characteristics. The 7-day lowest average streamflows with return periods of 10 and 2 years (7Q10 and 7Q2) are highly correlated with the catchment-scale response constants. The low-flow ratio Q95/Q50 (ratio of daily streamflow exceeded 95 and 50% of the time, respectively) varied between 0.3 and 0.5, indicating a high proportion of groundwater in the streamflow. The advantage of the regional regression model is its conceptual basis and use of the catchment-scale effective parameters. The method has the potential to be applied to ungauged catchments for estimating low-flow statistics from stream length and catchment area.     

Investigation on causes of the Siruyeh Landslide, West Semirom (Iran)

The Siruyeh landslide occurred at the eastern side of the Siruyeh valley, 22 km west of Semirom city, south of Esfahān on 25th March, 2005 with large dimensions (2,400 m long, 450 m wide with total area of 1 km²). The sliding mass blocked the Siruyeh River making a 35-m-high natural dam and 6-acre lake 570,000 m³ in volume that poses a potential threat for the area. The landslide occurred in soil and intensely weathered marls of the Tarbur and Kashkan Formations (upper Cretaceous–Paleocene age). The overall comparison and interpretation of the gathered evidence from satellite images, field trips, and laboratory tests show that the most important factors involved in triggering the Siruyeh landslide in order of importance are heavy precipitation and snow melt and intense concentration of faults and fractures as well as weathered and weak lithology.     

3D modeling and monitoring of karst system as a base for its evaluation and utilization: a case study from eastern Serbia

Beljanica Mountain in eastern Serbia is a part of the Carpathian Balkan arch (northern Alpine branch). It covers an area of about 300 km² and consists mostly of Jurassic and Cretaceous limestones. Numerous surface karst features, long caves and several large karstic springs located in Beljanica’s piedmont along the contact of karstic and non-karstic rocks are all indicators of an intense karstification. Currently, the large karstic water reserves of Beljanica Mountain are not properly utilized because of their distance from main consumers, the objection by national water managers that the springs lack a stable and sufficient discharge particularly during recession periods. Due to its unpolluted and high quality water, the area is a great prospect for future water supply, and provides an opportunity for artificial regulation and for the design and implementation of specific tapping structures. This paper includes an analysis of the created 3D ArcGIS model of karst interior and its correlation with historical and newly collected data of spring discharges and groundwater physico-chemical characteristics. The results of karst aquifer monitoring (both quantitative and qualitative) are linked with the results of extensive field geological and speleological survey of the upper non-saturated part of the karst (such as sinkholes, pits and caves) and with the investigation of the permanently saturated deeper part of the aquifer (including the diving methods). The model of karst interior is based on the data from the 69 caves, 15 sinks and 1,682 dolines (sinkholes) surveyed. The total length of the karst channels network, calculated using the GIS model and presented in a 3D environment, is 647 km. The catchment areas of five major springs that drain the areas are estimated to range from only 7 km² (Malo Vrelo Spring) to 124 km² (Vrelo Mlave Spring). The groundwater exploitable reserves of Beljanica karst aquifer are estimated to be over 4 m³/s. The waters are low mineralized, unpolluted and have a great potential for water supply.     

Landslide susceptibility analysis based on ArcGIS and Artificial Neural Network for a large catchment in Three Gorges region,China

A landslide susceptibility map is very important and necessary to efficiently prevent and mitigate the losses brought by natural hazard for a large area. For the purpose of landslide susceptibility analysis for the whole Xiangxi catchment (3,209 km²), Artificial Neural Network (ANN) analysis was applied as the main method. The whole catchment was divided into two parts: the training area and the implementation area. The backwater area (559 km²) of Xiangxi catchment was used as the training area for the ANN method. In the training area the correlations between the landslide distribution and its causative factors, which includes lithology, slope angle, slope curvature and river network, have been analyzed based on the geological map and digital elevation model (DEM). The back-propagation training algorithm in ANN was selected to train the sample data from the training area, which were composed of input data (causative factors) and target output data (landslide occurrence), in order to find the correlations between them. Based on these correlations and input data in the implementation area (causative factors), the network output data were obtained for the implementation area. In the end, a map of landslide susceptibility, which was established by network output data, was presented for Xiangxi catchment. ArcGIS was applied to extract and quantify input information from a DEM for susceptibility analysis and also to present the result visually. As a result, a landslide susceptibility map, in which 70 % of all landslides are rightly classified in the training area (backwater area), was created for Xiangxi catchment.