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Abstract: The Coorong is a choked coastal lagoon in South Australia that forms part of the terminal lake system at the end of the River Murray, Australia’s major river. It is an inverse estuary with a constricted channel connection to the sea at one end and extends parallel to the coast for more than 100 km away from this inlet. The present paper considers the physical dynamics of the Coorong, particularly its ecologically important salinity and water level regimes, and how these respond to connectedness with the ocean, barrage flows and meteorological conditions. The approach combines hydrodynamic modelling with measurements and considers temporal variation in the system ranging from seasonal to multi-decadal timescales. The Coorong is relatively unusual in that the major freshwater input occurs through barrages much closer to the estuary mouth than to its head. Thus, the barrage flows only ‘flush’ the Coorong between the barrages and the sea. Over most of its length, salt accumulating through evapo-concentration mixes back out of the system by fluctuating water motions caused by sea level variations propagating through the inlet channel and by wind. By scouring the inlet channel on a seasonal basis, barrage flows facilitate the penetration of sea level variations into the Coorong leading to enhanced along-lagoon mixing. Further, barrage flows freshen the waters near the seaward end of the system causing water of lower salt content than sea water to replace evaporative losses in its interior. By increasing the water depth in the system, barrage flows facilitate the exchange between the North and South Lagoons of the Coorong which are its two major basins. The modelling supported by measurements shows how the salinity regime in the Coorong appears to have responded to multi-year cycles of variation in discharge of the River Murray over the last 50 years. Even before the present drought, which has seen salinity in the South Lagoon exceed four times sea water, the lagoon was dominantly hypersaline. The modelling suggests that the significant reductions in freshwater inflows to the Coorong due to water resource development would have caused the South Lagoon to evolve from a state of being usually brackish to marine into its present hypersaline state. The conceptual understanding of the Coorong’s physical dynamics and their encapsulation in a hydrodynamic model are enabling strategies to be evaluated for alleviation of its present degraded condition, and for its improved future management. [Copyright &y& Elsevier]

The effect of day time vs. night time sprinkler irrigation on irrigation performance and tomato crop yield is assessed in this paper for the conditions of Tunisia. Field experiments were performed at the experimental station of Cherfech under two rectangular sprinkler spacings: 24 × 18m and 18 × 18m, denoted as plots M 1 and M 2, respectively. Results of performance evaluations indicate a significant effect of climatic and operation conditions on irrigation uniformity and wind drift and evaporation losses (WDEL). Experimental data were used to calibrate and validate a ballistic solid-set sprinkler irrigation simulation model and a soil-water-yield crop model. Based on the analysis of the main meteorological parameters during the irrigation season, the validated models were used to simulate night time irrigation (characterised by moderate wind speed and evaporative demand). Simulation results indicate that night time irrigation would greatly improve performance in comparison to day time operation: WDEL decreased from 24 to 7%, while irrigation uniformity increased from 50 to 64% in M 1 and from 71 to 80% in M 2. Simulated results showed that night time irrigation decreased relative yield losses (from 26 to 16% in M 1 and from 11 to 3% in M 2), as well as improving the spatial variability of crop yield (simulated yield CV in M 2 decreased from 17 to 6%). Adoption of night irrigation in the study area will finally depend on local socioeconomic and water management constraints. [Copyright &y& Elsevier]

Abstract: The nonparametric Mann–Kendall test was used to detect the trends of major hydroclimatic variables in the Tarim River Basin, the largest inland river basin in China for the period of 1960–2007. Results showed that both mean annual air temperature and precipitation experienced an increasing trend, while annual streamflow demonstrated a mixed trend of decreasing and increasing: The mountainous region upstream showed an increasing trend and the region downstream exhibited a decreasing trend. Impacts of the increased air temperature on streamflow have shown different characteristics depending on location and seasons: it has positive effect on the runoff at mountainous region due to snowmelt and glacier-melt in spring, but negative effect on the runoff at plain area due to the increase of actual evaporation in summer. In addition, human activity contributed to the declining of streamflow in the arid plain oases at downstream of the Tarim River Basin. The results obtained in this paper can be used as a reference for the planning and management of water resources to maintain the health of the river system. [Copyright &y& Elsevier]

Abstract: Vegetation restoration is one of the most common methods for combating desertification in northern China. The planting of shrubs on the southeast fringe of the Tengger Desert had significant effects on hydrological cycles, especially on the evaporation process. In this paper, a field experiment was conducted to investigate the effect of revegetation on evaporation process in a desert. The presence of shrubs reduced percolation from a lysimeter to zero. Caragana korshinskii Kom. showed greater evapotranspiration in the wetter of two study years, while Artemisia ordosica Krash. showed more evapotranspiration in the drier year. This was attributed to their different root distributions. The microlysimeter measurements showed that there was no significant difference in the evaporation rates between locations in the same quadrat, which means that the sparse vegetation had little effect on soil evaporation under the canopy, and thus modification of the microclimate was not a dominant factor in controlling soil evaporation in the revegetated desert area. The difference in soil evaporation between bare sand and the revegetated area was caused mainly by the formation of biological soil crusts. Simulated rainfall experiments showed that the crust had a retarding effect on evaporation under very low rainfall (⩽5mm), because its high proportion of finer particles slowed the evaporation rate, thus keeping the water in the soil surface longer. However, it allowed a higher evaporation rate under higher rainfall conditions. [Copyright &y& Elsevier]

Abstract: This paper describes the first results from a hydro-micrometeorological study designed to characterize the surface exchanges of water, and CO2, at a sky island forest site in the Santa Catalina Mountains. Data collected between June 2002 and December 2004 is used to describe the seasonal water/carbon dynamics of this ecosystem. During the severely dry pre-monsoon period (May–June) when vapor pressure deficit exceeded 2kPa, daytime relative humidity was below 20%, and soil moisture was less than 10%, the predominantly Douglas Fir/Pine forest severely reduced or curtailed its photosynthetic activity. At the onset of the monsoon season in July, the vegetation responded rapidly to the precipitation input, as soil moisture increased. The trees then remained relatively active throughout the fall and winter, particularly if there was adequate winter precipitation which promoted very high productivity into early spring. Given the relative importance of mountain island forest in this semi-arid landscape in terms of its contribution to area-average surface water and carbon exchange, the strong and somewhat unusual coupled seasonal cycles, this forest ecosystem likely has hitherto unrecognized implication for the seasonality of the regional-scale water and carbon cycle. [Copyright &y& Elsevier]

A new method was investigated for the improvement of salt-affected soils in regions where a sufficient amount of rainfall occurs in summer and the heat transfer coefficient and thermal conductivity of their soils were discussed. The subsoil is made coarse by soil sintering, and the capillarity from groundwater is cut-off. Thus, the rise to the soil surface of salts which are dissolved in the groundwater is prevented, and even if the groundwater level is high, the evaporation of water from the soil surface is reduced. In this paper, the heat transfer coefficient and thermal conductivity of the salt-affected soils were determined at the sintering temperatures (850–950°C) in order to obtain basic data for soil sintering. Based on these values, design and construction of a device for soil sintering will be described in a subsequent report. The results show that the heat transfer coefficient to the steel surface was about 40Wm−2K−1 in the range of 280–320°C. The heat transfer coefficient of the studied soil surfaces was about 60Wm−2K−1 in the range of 700–1000°C regardless of types of soil. The thermal conductivity of pseudogley soil from Japan was about 0·1Wm−1K−1 (specimen temperature was about 900°C, and soil water content was 0% dry basis) when the solid ratio was less than 0·38, and it was about 0·3Wm−1K−1 when the solid ratio was more than 0·38. The thermal conductivity of solonchak and solonetz from China was 0·1–0·3Wm−1K−1 (specimen temperature was about 900°C, and soil water content was 0% dry basis) regardless of the types of soil and horizon. The thermal conductivity of the upper layer soils of the solonchak and solonetz did not increase with greater solid ratio because salts contained in them make for a low thermal conductivity. [Copyright &y& Elsevier]

Abstract: The Gambia River is one of the last aquatic ecosystems in West Africa that has not yet been affected by strong environmental changes and human disturbances. In contrast to the neighbouring Casamance and Sine Saloum estuaries, the Gambia estuary is free of major climatic perturbation and remains a “normal” estuary, with a salinity range from freshwater to 39. The present paper aims to study the spatial and seasonal variability of fish assemblages in this estuary in terms of bio-ecological categories and of their relation with some environmental variables. Four surveys were conducted, from June 2001 to April 2002, in order to cover the major hydroclimatic events, at 44 sampling sites along the lower, intermediate and upper zones of the Gambia estuary (up to 220km). Fish assemblages were sampled using a purse seine net, fish were identified to species level and environmental variables such as water depth, transparency, salinity, temperature and percentage oxygen saturation were measured. The main spatial structure of the fish assemblages and its seasonal changes were first studied using the STATIS-CoA multitable method. The combination of fish assemblages and environmental variables was then analysed using the STATICO method, designed for the simultaneous analysis of paired ecological tables. A total of 67 species were observed, belonging to all bio-ecological categories characterizing West African estuaries. The marine component of the community was largely dominant throughout the estuary, while the freshwater component was permanently observed only in the upstream zone. The main spatial structure was a longitudinal gradient contrasting marine and freshwater affinity assemblages, with strong seasonal variations. The most complete gradient was observed in December, at the beginning of the dry and cool season, while in June, at the end of the dry and warm season, there was the least structured gradient. The role of salinity, always correlated with temperature, was emphasized, while turbidity appeared to be another important factor. Oxygen and depth did not play a major role at the estuary scale. The relative importance of the bio-ecological categories varied according to the season and the distance to sea. Stable fish assemblages were observed in the lower zone at the end of the dry season, in the upper zone during the flood and in the middle zone throughout the year. In some situations, a relative inadequacy between fish assemblages and their environment was noticed. The present study contributes to the definition of the functioning of a “normal” West African estuary, the Gambia estuary, with balanced effects of marine and freshwater influences and the presence of all bio-ecological categories. The Gambia estuary can therefore be considered to be a reference ecosystem for further comparisons with other tropical estuarine ecosystems, subjected to natural or artificial perturbations. [Copyright &y& Elsevier]

Abstract: The degree to which incident wind waves are attenuated over intertidal surfaces is critical to the development of coastal wetlands, which are, amongst other processes, affected by the delivery, erosion, and/or resuspension of sediment due to wave action. Knowledge on wave attenuation over saltmarsh surfaces is also essential for accurate assessments of their natural sea-defence value to be made and incorporated into sea defence and management schemes. The aim of this paper is to evaluate the use of a digital photographic method for the quantification of marsh vegetation density and then to investigate the relative roles played by hydrodynamic controls and vegetation density/type in causing the attenuation of incident waves over a macro-tidal saltmarsh. Results show that a significant statistical relationship exists between the density of vegetation measured in side-on photographs and the dry biomass of the photographed vegetation determined through direct harvesting. The potential of the digital photographic method for the spatial and temporal comparison of marsh surface vegetation biomass, density, and canopy structure is highlighted and the method was applied to assess spatial and seasonal differences in vegetation density and their effect on wave attenuation at three locations on a macro-tidal saltmarsh on Dengie Peninsula, Essex, UK. In this environmental setting, vegetation density/type did not have a significant direct effect on wave attenuation but modified the process of wave transformation under different hydrodynamic conditions. At the two locations, characterised by a relatively tall canopy (15–26cm) with biomass values of 430–500gm−2, dominated by Spartina spp. (>70% of total dry biomass), relative incident wave height (wave height/water depth) is identified as a statistically significant dominant positive control on wave attenuation up to a threshold value of 0.55, beyond which wave attenuation showed no significant further increase. At the third location, characterised by only slightly less biomass (398gm−2) but a shorter (6cm) canopy of the annual Salicornia spp., no significant relationship existed between wave attenuation and relative wave height. Seasonally (between September and December) significant temporal increase/decrease in vegetation density occurred in one of the Spartina canopies and in the Salicornia canopy, respectively, and led to an expected (but not statistically significant) increase/decrease in wave attenuation. The wider implications of these findings in the context of form–process interactions on saltmarshes and their effect on marsh evolution are also discussed. [Copyright &y& Elsevier]

The time-series models introduced in this paper were developed to estimate and forecast temperature and humidity dynamics in an unheated, naturally ventilated greenhouse in Lisbon, Portugal. External and internal climatic data recorded over four consecutive months during the tomato (Lycopersicon esculentum, Mill) growing season were used to build and validate forecasting models for simulating environmental conditions inside the greenhouse. The statistical models were assessed with co-integration and error correction methods, using hourly data. The main variables considered to estimate the internal air temperature were external temperature, ventilation rate and solar radiation. Internal relative humidity was predicted primarily from external relative humidity, ventilation rate and evapotranspiration. Internal greenhouse air temperature and relative humidity were closely related to solar radiation, external air temperature and ventilation rate. Despite the large number of parameters involved, both models provided a reliable prediction of the system dynamics. A comparison of measured and simulated data showed that the models were able to forecast internal greenhouse conditions reasonably well. [Copyright &y& Elsevier]