Bias corrected daily climate projections from five global circulation models (GCMs) under the RCP8.5 emission scenarios were fed into a calibrated Variable Infiltration Capacity (VIC) hydrologic model to project future hydrological changes in China. The standardized precipitation index (SPI), standardized runoff index (SRI) and standardized soil moisture index (SSWI) were used to assess the climate change impact on droughts from meteorological, agricultural, and hydrologic perspectives. Changes in drought severity, duration, and frequency suggest that meteorological, hydrological and agricultural droughts will become more severe, prolonged, and frequent for 2020-2049 relative to 1971-2000, except for parts of northern and northeastern China. The frequency of long-term agricultural droughts (with duration larger than 4 months) will increase more than that of short-term droughts (with duration less than 4 months), while the opposite is projected for meteorological and hydrological droughts. In extreme cases, the most prolonged agricultural droughts increased from 6 to 26 months whereas the most prolonged meteorological and hydrological droughts changed little. The most severe hydrological drought intensity was about 3 times the baseline in general whereas the most severe meteorological and agricultural drought intensities were about 2 times and 1.5 times the baseline respectively. For the prescribed local temperature increments up to 3°C, increase of agricultural drought occurrence is predicted whereas decreases or little changes of meteorological and hydrological drought occurrences are projected for most temperature increments. The largest increase of meteorological and hydrological drought durations and intensities occurred when temperature increased by 1°C whereas agricultural drought duration and intensity tend to increase consistently with temperature increments. Our results emphasize that specific measures should be taken by specific sectors in order to better mitigate future climate change associated with specific warming amounts. It is, however, important to keep in mind that our results may depend on the emission scenario, GCMs, impact model, time periods and drought indicators selected for analysis.

No abstract

No abstract

Soil seed banks are an important component of plant community diversity in ephemeral wetlands, allowing many species to persist through unpredictable periods of flood and drought. Spatial variation of extant vegetation in such habitats commonly reflects patterns of flood history and often varies predictably between broadly differing hydro-geomorphic habitat types. Here we investigate whether spatial variation of soil seed banks is similarly controlled by fluvial processes at this scale. Results are presented from a seedling emergence trial using samples collected from a range of habitat types, and at different scales within these, in the ephemeral Narran Lakes system in semi-arid Australia. Composition and structure of soil seed banks varied significantly between habitat types reflecting broad differences in flood frequency. As predicted, germinable seed abundance was found to be highest in intermediately flooded habitats. Variability in soil seed bank composition at a local scale was also found to be influenced by hydrology with greater spatial heterogeneity evident in the river channel as well as amongst the least frequently inundated riparian and floodplain habitats.

No abstract

No abstract

Wetlands, particularly those in semi-arid or arid environments, are hotspots of biological diversity and productivity. Water resource managers are therefore increasing their efforts to conserve wetlands from environmental degradation. To do this, they require a thorough understanding of the wetting and drying regimes of these wetlands, and how potential land use, climate change and water resource development might affect inundation patterns. Hydrologic models can help to enhance this understanding, and to predict and assess future impacts. However, for semi-arid environments, data to assist in model construction is scarce. This paper presents a new method for developing a water balance model for a semi-arid wetland, the Narran Lakes ecosystem in eastern Australia. This method combines hydraulic (improving our understanding of water movement through a wetland) and hydrologic (improving our predictive capability for inundation levels) models and satellite imagery (acting as calibration and validation data) to produce a predictive model of wetland inundation. We show that this coupled hydraulic–hydrologic model yields inundation patterns commensurate with those that actually occurred over more than 30 years. The model results indicate that current inundation levels are at historical lows, which is most likely associated with a naturally occurring drought and increasing water resource development upstream.

No abstract