Trends in floods in West Africa: analysis based on 11 catchments in the region
Summary: The region of West Africa is undergoing important climate and environmental changes affecting the magnitude and occurrence of floods. This study aims to analyze the evolution of flood hazard in the region and to find links between flood hazards pattern and rainfall or vegetation index patterns.
Hydrol. Earth Syst. Sci., 19, 4707-4719, doi:10.5194/hess-19-4707-2015, 2015
Defining high-flow seasons using temporal streamflow patterns from a global model
Summary: This paper presents a global approach to defining high-flow seasons by identifying temporal patterns of streamflow. Simulations of streamflow from the PCR-GLOBWB model are evaluated to define dominant and minor high-flow seasons globally, and verified with GRDC observations and flood records from Dartmouth Flood Observatory.
Hydrol. Earth Syst. Sci., 19, 4689-4705, doi:10.5194/hess-19-4689-2015, 2015
Reconciling high-altitude precipitation in the upper Indus basin with glacier mass balances and runoff
Summary: The water resources of the upper Indus river basin (UIB) are important for millions of people, yet little is known about the rain and snow fall in the high-altitude regions because of the inaccessibility, the climatic complexity and the lack of observations. In this study we use mass balance of glaciers to reconstruct the amount of precipitation in the UIB and we conclude that this amount is much higher than previously thought.
Hydrol. Earth Syst. Sci., 19, 4673-4687, doi:10.5194/hess-19-4673-2015, 2015
The SPARSE model for the prediction of water stress and evapotranspiration components from thermal infra-red data and its evaluation over irrigated and rainfed wheat
Summary: The paper presents a new model (SPARSE) to estimate total evapotranspiration as well as its components (evaporation and transpiration) from remote-sensing data in the thermal infra-red domain. The limits of computing two unknowns (evaporation and transpiration) out of one piece of information (one surface temperature) are assessed theoretically. The model performance in retrieving the components as well as the water stress is assessed for two wheat crops (one irrigated and one rainfed).
Hydrol. Earth Syst. Sci., 19, 4653-4672, doi:10.5194/hess-19-4653-2015, 2015
Novel indices for the comparison of precipitation extremes and floods: an example from the Czech territory
Summary: Three proposed indices combine return periods of precipitation totals or discharges with the size of the affected area. Precipitation indices also determine actual duration of either extreme or seasonally abnormal precipitation events. A unified design of the indices enables one to easily compare inter-annual and seasonal distributions of events, which is demonstrated by 50 maximum events in the Czech Republic during the period 1961-2010, including the June 2013 floods.
Hydrol. Earth Syst. Sci., 19, 4641-4652, doi:10.5194/hess-19-4641-2015, 2015
From runoff to rainfall: inverse rainfall–runoff modelling in a high temporal resolution
Summary: Especially in alpine catchments, areal rainfall estimates often exhibit large errors. Runoff measurements are, on the other hand, one of the most robust observations within the hydrological cycle. We therefore calculate mean catchment rainfall by inverting an HBV-type rainfall-runoff model, using runoff observations as input. The inverse model may e.g. be used to analyse rainfall conditions of extreme flood events or estimation of snowmelt contribution.
Hydrol. Earth Syst. Sci., 19, 4619-4639, doi:10.5194/hess-19-4619-2015, 2015
Climate change and its impacts on river discharge in two climate regions in China
Summary: This study quantified the climate impact on river discharge in the River Huangfuchuan in semi-arid northern China and the River Xiangxi in humid southern China. Climate projections showed trends toward warmer and wetter conditions, particularly for the River Huangfuchuan. The main projected hydrologic impact was a more pronounced increase in annual discharge in both catchments. Peak flows are projected to appear earlier than usual in the River Huangfuchuan and later than usual in River Xiangxi.
Hydrol. Earth Syst. Sci., 19, 4609-4618, doi:10.5194/hess-19-4609-2015, 2015
Review and classification of indicators of green water availability and scarcity
Summary: The paper draws attention to the fact that green water (soil moisture returning to the atmosphere through evaporation) is a scarce resource, because its availability is limited and there are competing demands for green water. Around 80 indicators of green water availability and scarcity are reviewed and classified based on their scope and purpose of measurement. This is useful in order to properly include limitations in green water availability in water scarcity assessments.
Hydrol. Earth Syst. Sci., 19, 4581-4608, doi:10.5194/hess-19-4581-2015, 2015
Large-scale hydrological modelling by using modified PUB recommendations: the India-HYPE case
Summary: We modify the recommendations for flow predictions in ungauged catchments to address the challenges at the large scale. We use examples from the HYPE hydrological model set-up across 6000 subbasins for the Indian subcontinent. Multi-basin modelling reveals the spatial patterns of catchment functioning and dominant flow processes across the hydroclimatic gradient. The model set-up procedure according to the PUB recommendations brought insights into where the single model structure is inadequate.
Hydrol. Earth Syst. Sci., 19, 4559-4579, doi:10.5194/hess-19-4559-2015, 2015
Climate response to Amazon forest replacement by heterogeneous crop cover
Summary: This study expands upon previous Amazon deforestation modeling studies by using realistic heterogeneous crop cover as replacement vegetation and diagnoses the changes in land-atmosphere coupling due to land use change. With the use of an interactive crop model, the impact that irrigation has on land-atmosphere coupling when using crops as a replacement vegetation is analyzed. This study also provides documentation on the development of tropical crops for CLM4.5.
Hydrol. Earth Syst. Sci., 19, 4547-4557, doi:10.5194/hess-19-4547-2015, 2015
Nonlinear effects of locally heterogeneous hydraulic conductivity fields on regional stream–aquifer exchanges
Summary: Computation experiments found the effects of small-scale heterogeneities do influence estimates of aquifer--stream exchanges. The effects are nonlinear in the sense that simulated discharges from aquifers to streams are systematically lower than discharges produced by a base model parameterized with coarse effective K. Although aquifer heterogeneities are uncorrelated at local scales, they appear to induce coherent slow-paths in groundwater fluxes that in turn reduce aquifer-stream exchanges.
Hydrol. Earth Syst. Sci., 19, 4531-4545, doi:10.5194/hess-19-4531-2015, 2015
A conceptual, distributed snow redistribution model
Summary: Temperature index melt models often lead to snow accumulation in high mountainous elevations. We developed a simple conceptual snow redistribution model working on a commonly used grid cell size of 1x1km. That model is integrated in the hydrological rainfall runoff model COSERO. Applying the model to the catchment of Oetztaler Ache, Austria, could prevent the accumulation of snow in the upper altitudes and lead to an improved model efficiency regarding discharge and snow coverage (MODIS).
Hydrol. Earth Syst. Sci., 19, 4517-4530, doi:10.5194/hess-19-4517-2015, 2015
Quantitative analysis of biogeochemically controlled density stratification in an iron-meromictic lake
Hydrol. Earth Syst. Sci., 19, 4505-4515, doi:10.5194/hess-19-4505-2015, 2015
Effects of mountain tea plantations on nutrient cycling at upstream watersheds
Summary: We summarize our findings as follows: (1) the mountain watersheds are vulnerable to agriculture expansion; (2) proper spatial configuration of agricultural lands in mountain watersheds can mitigate the impact of agriculture on NO3- output by 70%; and (3) the reconstructed element fluxes for the watersheds indicate excessive leaching of N and P, and additional loss of N to the atmosphere via volatilization and denitrification, which likely resulted from excessive fertilizer use.
Hydrol. Earth Syst. Sci., 19, 4493-4504, doi:10.5194/hess-19-4493-2015, 2015
Quantification of the contribution of the Beauce groundwater aquifer to the discharge of the Loire River using thermal infrared satellite imaging
Summary: This work shows that satellite thermal infrared images (LANDSAT) can be used to locate and quantify groundwater discharge into a large river (Loire River, France - 100 to 300 m wide). Groundwater discharge rate is found to be highly variable with time and space and maximum during flow recession periods and in winter. The main identified groundwater discharge area into the Loire River corresponds to a known discharge area of the Beauce aquifer.
Hydrol. Earth Syst. Sci., 19, 4479-4492, doi:10.5194/hess-19-4479-2015, 2015
Evaluating the utility of satellite soil moisture retrievals over irrigated areas and the ability of land data assimilation methods to correct for unmodeled processes
Hydrol. Earth Syst. Sci., 19, 4463-4478, doi:10.5194/hess-19-4463-2015, 2015
SACRA – a method for the estimation of global high-resolution crop calendars from a satellite-sensed NDVI
Summary: This study aims to develop a new global data set of a satellite-derived crop calendar (SACRA) and to reveal its advantages and disadvantages compared to other global products. The cultivation period of SACRA is identified from the time series of NDVI; therefore, SACRA considers current effects of human decisions and natural disasters. The difference between the estimated sowing dates and other existing products is less than 2 months (< 62 days) in most areas.
Hydrol. Earth Syst. Sci., 19, 4441-4461, doi:10.5194/hess-19-4441-2015, 2015
Determining the stable isotope composition of pore water from saturated and unsaturated zone core: improvements to the direct vapour equilibration laser spectrometry method
Summary: Improvements and limitations to the measurement δ2H and δ18O of pore waters in geologic core samples using laser spectrometry are presented. These included the use of a δ2H spike to assess the extent of drill fluid contamination and the effect of storage time and type of sample bag on pore water values.
Hydrol. Earth Syst. Sci., 19, 4427-4440, doi:10.5194/hess-19-4427-2015, 2015
Impact of the Three Gorges Dam, the South–North Water Transfer Project and water abstractions on the duration and intensity of salt intrusions in the Yangtze River estuary
Summary: This paper demonstrates a method for calculating the probability of long-duration salt intrusions in the Yangtze Estuary and examines the impact of the Three Gorges Dam, the South-North Water Transfer Project and local abstractions on that probability. The relationship between river discharge and the intensity and duration of saline intrusions is shown to be probabilistic and continuous. That probability has more than doubled under the normal operating rules for those projects.
Hydrol. Earth Syst. Sci., 19, 4411-4425, doi:10.5194/hess-19-4411-2015, 2015
Identification of spatial and temporal contributions of rainfalls to flash floods using neural network modelling: case study on the Lez basin (southern France)
Summary: Flash floods are important hazards in urbanised zone and constitute important human and financial stakes. This paper applies a novel methodology, KnoX, dedicated to extract knowledge from a neural network model. It was shown that KnoX method could help to better characterize processes of both surface and underground floods. A case study is chosen in France: the Lez karst hydrosystem whose river crosses the city of Montpellier (400 000 inhabitants). Results will help flood warning services.
Hydrol. Earth Syst. Sci., 19, 4397-4410, doi:10.5194/hess-19-4397-2015, 2015