This paper explores the consideration and implication of calibration period on the modelled climate change impact on future runoff. Hide

Scenario projections of the dynamics of meteocharacteristics for basins of the Olenek and Indigirka rivers in the 21 century have been obtained for four global climate change scenarios. The projections have been used to calculate scenarios of possible changes in water balance components for the selected basins in the 21 century. The calculation procedure involves a physically-based model for interaction between the land surface and the atmosphere SWAP and climate scenario generator. Hide

This paper provides an overview of this IAHS symposium and PIAHS proceeding on “hydrologic nonstationarity and extrapolating models to predict the future”. The paper provides a brief review of research on this topic, presents approaches used to account for nonstationarity when extrapolating models to predict the future, and summarises the papers in this session and proceeding. Hide

Flow regimes of rivers will be different in the future, but how different is uncertain. Water resources decisions will rely on practical simulation tools that are sensitive to changes, can assimilate change information and flexible enough to accommodate new understanding. This paper presents some tools that can address these issues in southern Africa. Appropriate tools are available but we need more reliable forcing and model validation data and methods for making decisions with uncertain data. Hide

Catchment response can be influenced by man’s activities as well as natural forces like climate, and understanding how stream flow is affected by such activities is important in a changing world, particularly in developing countries. Data for the Bani River in Africa show a steady decrease in the groundwater component of stream flow. This paper shows that the decrease appears to be driven by increased water use in the catchment, and has resulted in the river ceasing to flow in the dry season. Hide

We used a newly developed river system model to analyse the influence of anthropogenic development and water use on streamflow and to partition this influence from climate variability/change impact on streamflow in a regulated river system. The results have demonstrated that the water storages and anthropogenic water use have significant influence on trends in streamflow. Hide

Socio-economic and hydroclimatic data were integrated in a modeling framework to simulate water resources and demand. We successfully modeled water stress changes in space and time in two basins over the past 40 years, and explained changes in discharge by separating human and hydroclimatic trends. The framework was then applied under 4 combinations of climate and water use scenarios at the 2050 horizon. Results showed that projected water uses are not sustainable under climate change scenarios. Hide

The land surface model SWAP was found to be robust and can be applied for climate change studies. The river runoff projections up to 2100 were calculated for two greenhouse gas emission scenarios: RCP8.5 and RCP4.5. Scatter among SWAP’s projections due to application of different post-processing techniques for correcting biases in meteorological forcing data did not exceed 8%, while differences between changes in runoff projected by two models are much larger. Hide

This study proposed the nonstationary generalized logistic model including time-dependent parameters. The parameters of proposed model are estimated using the method of maximum likelihood based on the Newton-Raphson method. In addition, the proposed model is compared by Monte Carlo simulation to investigate the characteristics of models and applicability. Hide

The aim of this study is to clarify the properties of the parameters in the storage-discharge relations by carrying out a sensitivity analysis of efficiency using a hydrological model. The study basins are four mountainous basins in Japan with different climates and geologies. The results confirm that the two parameters in the storage-discharge relations can be expressed in an inversely proportional relationship. Hide

This study explores various hydrological projections while accounting for propagation uncertainties that arise from the methods used to generate climate projections and to simulate streamflow responses from four basins in the Mediterranean. Hydrological projections based on temperature ensemble scenarios generally agree on a runoff decrease during all seasons while projections mixing temperature and precipitation ensemble scenarios only agreed on a trend to runoff decrease during spring. Hide

7 CMIP5 climate models under RCP8.5 emissions scenarios were downscaled by means of bilinear interpolation and bias correction. The downscaled results are evaluated over China by comparing with the England Reanalysis CRU3.1. Time series of SPI has been used to identify drought from 20th century to 21st century over China. the SPI show a slightly increasing trend in the future period for the most parts of China, but drought in Southwest region of China will become the norm in the future. Hide

Regional frequency analysis gives a quantity for the design of hydaulic structures. The stationarity of record shuld be assumed for its application. Climate change and anthropogenic factors can, however, violate this assumption. Nonstatonary regioanl frequency analysis, therefore, is required. There can be four types of index flood models as a representative technique for nonstationary regional frequency analysis. This research focused on the evaluation of their perfomances. Hide

The common use of "potential evaporation" to estimate actual evapotranspiration or to describe the suitability of a given climate for plant growth may lead to wrong conclusions about the consequences of climate change on plant growth and water relations. Wind speed in particular can have opposite effects on potential evaporation and transpiration from plant leaves. Therefore, we recommend to avoid using the concept of potential evaporation in relation to plants and transpiration from leaves. Hide

Hydrologic models use daily precipitation and potential evapotranspiration for streamflow estimation. The effect of an increase in rainfall intensity on the long-term water balance is not adequately accounted for in these hydrologic models. This study, using data from a forested watershed in France, shows that the effect of peak rainfall intensity on runoff prediction is insignificant for two models tested, and model performance is unlikely to improve when peak daily precipitation is included. Hide

Using the variance rather than the mean as the tested variable is shown to be more consistent for assessing non-stationarity of annual maximum daily rainfalls at eight rainfall stations in Dublin, Ireland. Observed step changes in variance are temporally consistent with a positive phase of the NAO suggesting they result from a climate change signal. Allowing for the step changes in design rainfalls produced increases from 5 to 16% for the 5-year event and from 20 to 41% for the 100-year event. Hide

This study uses data from 7 gauging stations in the Xingu basin and 14 stations in the Tapajós basin. Results indicate opposite monotonic trends at the 95% confidence level for different regions in the basins, and for different flow regimes. For the Xingu river basin, trends in the minimum flow for different sub-basins even out at the Altamira station, near its outlet. For the Tapajós river, the southeastern part of the basin has increasing trends, while the southwestern part decreases. Hide

Snowpack properties vary over distance. Water resources managers use operational data to estimate streamflow, while scientists use snow data models to understand climate and hydrology. We suggest that there is the individual measurements in a snowcourse be used to address uncertainty. Further, over the long term trends may not be obvious but increasing and decreasing trends can exist over shorter time periods, as seen in Northern Colorado. Such trends mirror global temperature patterns. Hide

This paper examines the complex interactions and feedbacks between many variables and processes within Owo catchment and analyses the future ability of this semi-urban watershed in sustaining water supply in the face of cumulative environmental change. Total length of streams within the catchment reduced from 622.24 km in 1964 to 556 km in 2010, while stream density reduced from 0.53 in 1964 to 0.47 in 2010 an indication of shrinking hydrological network. Hide

In our research, we found the climate change has resulted in larger variation of groundwater recharge and surface runoff in mountainous catchment. The middle and downstream areas are considered to be the main groundwater recharge areas. The rainfall intensity had a great impact on the changes of the groundwater level. The recharge resources may will decrease and groundwater storage will decline under the trend of decreasing precipitation in the future. Hide

A approach for non-stationary hydrological frequency analysis is proposed. In this method, an assumption is done that the variation hydrological series in a big time window owns an expected vibration center (EVC), which is a linear combination of the two mean values of the two subsample series. Then using the EVC to reconstruct non-stationary series to meet the requirement of stationary. Hide

By taking an example of Allen’s formula as a hydrological model based on long-term data at a Chinese site, the relationships between driving forces and responses for average, minimum and maximum values at daily, monthly and annual scale are revealed. It indicates due to the relationships’ nonlinearity a routine model may not be able to catch hydrological responses extreme from extreme driving events and it is even more so for future. Finding a primary driver is one of the ways for improvements. Hide

In this paper, we employ two methods, i.e. hydrological sensitivity analysis and hydrological model simulation, to investigate the effect of climate variability and climatic change on actual evapotranspiration (Ea) within the Laohahe basin during 1964-2009. Hide

Digital elevation models acquired with a terrestrial laser scanner were used to study summerly erosion on steep slopes. An existing physical event-based erosion model approach was tested on theses slopes and validated with the laser scanning values. Modeled and scanned values are in 98.4% agreement. Additionally a statistical modeling approach was used to compare the results with a previous study in a nearby area. The comparison showed a good applicability of the model on different slopes. Hide

This study assesses the impact of the land use and climate changes between 1967−2008 on the streamflow and sediment yield in Tapacurá River basin (Brazil) using the SWAT model. The model was calibrated and validated. The results show that the land cover and climate change affected the basin hydrology, decreasing the streamflow and sediment yield. The process changes are arising mainly due to the land cover/use variability, but mainly due to the decreasing in the rainfall rates during 1995−2008. Hide

This paper explores the reliability of low-flow simulations by conceptual models in a semi-arid, Andean catchment facing climate variability and water-use changes. A parsimonious hydrological model (GR4J) was combined with a model of irrigation water-use (IWU) to provide a new model of the catchment behavior (called GR4J/IWU). The original GR4J model and the GR6J model were also used as benchmarks to evaluate the usefulness explicitly accounting for water abstractions. Hide

The main driving force of climate variability and in hydrologic cycle is the solar radiation.Over the period 1850 to 1996 was observed steady increase of sunspots on the Sun. During this period also was observed an increase in temperature in the Northern Hemisphere.The study presents an analysis of river runoffs trends in the past,proposes a methodology to calculate an influence of solar activity on rivers discharge and air temperature.River runoffs trends for the period up to 2030 have shown. Hide

Most of the forested headwater catchments are an important source of water supply in many parts of the world. A prime example is southeast Australia where forests supply major river systems and towns and cities with water. It is critical for an informed and adaptive water resource management to understand changes in streamflow caused by vegetation changes in these headwater forest catchments. Natural disturbances such as bushfires and anthropogenic activities like forestation, deforestation, or Hide