ALBERT

Description: Restoration and water table control on peatlands to limit fire risk are national priorities in Indonesia. The present study was initiated at Padang Island, Sumatra, to increase understanding on peatland hydrology in the tropic. At the pilot site, water table and precipitation were monitored at different stations. The results show variation in water table depths (WTDs) over time and space due to spatial and temporal variability in rain intensity and drainage networks. In part of the island, large-scale drainage for plantations led to deep WTD (−1.8 m) and high WTD recession rates (up to 3.5 cm/day). Around villages, farm-scale drainages had a smaller impact with a lower recession rate (up to 1.8 cm/day) and shallow WTD, typically below −0.4 m, the threshold for sustainable peatland management in Indonesia. The recession rates levelled off at 1.0 cm/day near the drained forest/plantation and at 0.5 cm/day near the farm. Deeper layers had much lower specific yield (Sy), 0.1 at −1.5 m depth, compared with top peat soils with Sy up to 0.3. Proximity to drainages extended discharge flow to deeper layers. The results highlighted the severity of peatland drainage impact on most coastal zones of Padang Island, which have intensive drainage networks.

Description: In this study, the snowmelt runoff model (SRM) was employed to estimate the effect of snow on the surface flow of Aji-Chay basin, northwest Iran. Two calibration techniques were adopted to enhance the calibration. The multi-station calibration (MSC) and single-station calibration (SSC) strategies applied to investigate their effects on the modeling accuracy. The runoff coefficients (cs and cr) were selected as calibration parameters because of their uncertainty in such an extended basin. To determine the most substantial input of the model which is the snow-covered area (SCA) from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor imagery, MOD10A2 images were collected with spatial and temporal resolutions of 500 meters and 8 days, respectively. The results show an average of 15% improvement in the model performance in the MSC strategy from the data period of 2008–2012. Also, an appropriate agreement with physical characteristics of the study area could be seen for the calibration parameters. The contribution of snowmelt in the river flow reaches its peak in April and May, then with increasing temperature, the contribution decreased gradually. Furthermore, analysis of parameters indicates that the SRM is sensitive to recession coefficient and runoff coefficients.

Description: This work reports the effects of five pipe materials on reverse osmosis (RO)-reclaimed water quality in a large pilot-scale distribution system. These materials includes cast iron (CI), cast iron with cement-mortar lining (CML), stainless steel (SS), PVC, and PE. Long-term running tests for 96 hours are conducted with water quality parameters monitored online and analyzed offline. The results showed that red water appeared in CI pipe due to iron corrosion. The pH and TDS increased during the long-term test. Alkali–silica reaction in CML pipe led to a high increase of pH from 6.3 to 11.4, and TDS from 51 to 230 mg/L. Water quality deterioration was not observed in SS, PVC, and PE pipes. Residual chlorine decay occurred in all the five material pipes with the decay rate order of CI ≫ CML 〉 SS ≈ PVC ≈ PE. Ion concentration variation was also followed during the tests. Fe and Mn ions were detected in CI pipe and Ca, Si, Al, and S were detected in CML pipe. No detectable ion release was found in SS, PVC, and PE pipes. A kinetic model was postulated for the detected ion release with the mechanisms discussed in-depth.

Description: To explore the effects of mixed irrigation on soil and crops, a pot experiment was conducted in two salinity levels of brackish water, four levels of mixed brackish-reclaimed water and freshwater irrigation as the control. The soil Na-Cl to Ca-SO4 contents changed, and activities of soil alkaline phosphatase and polyphenol oxidase changed, exhibiting a ‘V’-shaped curve with increasing the proportion of reclaimed water in the mixture. At the same brackish-reclaimed water level, there were no significant differences in alkaline phosphatase and polyphenol oxidase activities except for soil alkaline phosphatase activity decreasing significantly with the increase in salinity under brackish water irrigation. Mixed irrigation obviously improved superoxide dismutase activity but no significant influences on aboveground dry weight, underground biomass or crop physiological indexes (chlorophyll, soluble protein, malondialdehyde, peroxidase, catalase). Based on the integrated biological response index version 2 (IBRv2), the deviation of reclaimed water irrigation was the smallest, followed by 1:1 and 1:2 (3, 5 g/L brackish water salinities, respectively), with IBRv2 values of 7.94, 12.55 and 16.04. Therefore, considering the soil-crop characteristics, limited daily water amount and inadequate pipeline facilities for reclaimed water, the brackish-reclaimed water ratio should be 1:1 and 1:2 at 3, 5 g/L of brackish water, respectively.

Description: The UK standard for estimating flood frequencies is outlined by the flood estimation handbook (FEH) and associated updates. Estimates inevitably come with uncertainty due to sampling error as well as model and measurement error. Using resampling approaches adapted to the FEH methods, this paper quantifies the sampling uncertainty for single site, pooled (ungauged), enhanced single site (gauged pooling) and across catchment types. This study builds upon previous progress regarding easily applicable quantifications of FEH-based uncertainty estimation. Where these previous studies have provided simple analytical expressions for quantifying uncertainty for single site and ungauged design flow estimates, this study provides an easy-to-use method for quantifying uncertainty for enhanced single site estimates.

Description: The objective of this paper is to compare, under Dutch market conditions, the energy consumption and net costs of membrane-based advanced treatment processes for three water reuse types (i.e. potable, industrial, agricultural reuse). The water source is municipal wastewater treatment plant effluent. Results indicate that the application of reverse osmosis is needed to reclaim high quality water for industrial and potable reuse but not for irrigation water which offers significant energy savings but may not lead automatically to lower net costs. While a reclamation process for industrial reuse is economically most promising, irrigation water reclamation processes are not cost effective due to low water prices. Moreover, process operational expenditures may exceed capital expenditures which is important for tender procedures. A significant cost factor is waste management that may exceed energy costs. Water recovery rates could be significantly enhanced through the integration of a softener/biostabilizer unit prior to reverse osmosis. Moreover, the energy consumption of wastewater reclamation processes could be supplied on-site with solar energy. The possibility of designing a ‘fit for multi-purpose’ reclamation process is discussed briefly. This comparative analysis allows for better informed decision making about which reuse type is preferably targeted in a municipal wastewater reuse project from a process design perspective.

Description: The three-river headwaters region (TRHR) is the birthplace of the Yangtze River, the Yellow River and the Lantsang River in China. Based on the grid surface precipitation data released by China Meteorological Administration (CMA), this paper evaluated the accuracy and error components of four near-real-time satellite precipitation products (GSMaP-NRT, GSMaP-MVK, IMERG-Early and IMERG-Late) in the era of a GPM (Global Precipitation Measurement) in TRHR. The conclusions are as follows: (1) The precipitation in TRHR is concentrated in the east and south, and the precipitation in the west is very low. IMERG (Early and Late) has a good spatial distribution of precipitation, while GSMaP has an obvious spatial smoothing of precipitation distribution, and does not better highlight the local precipitation characteristics. (2) The inversion accuracy of the satellite products is the best in the source region of the Lantsang River, followed by the source region of the Yellow River. The satellite products all show the lower correlation coefficient and serious underestimation of precipitation in the west of the TRHR. In addition, the closer to the west of the TRHR, the lower hit rate and the higher false alarm rate of the satellite products, especially the NRT and MVK products. In the eastern margin of the Yellow River headwater region and the Lantsang River headwater Region, RMSE and overestimated precipitation were higher in NRT and MVK, and FAR was higher in spite of higher POD and CSI. (3) The errors of GSMaP in the source region of the Yellow River and the Lantsang River are mainly caused by misreporting precipitation and overestimating the precipitation level, while the errors of GSMaP in the west of the TRHR are mainly caused by missing measurements of precipitation events. The underestimated precipitation of IMERG mainly comes from the missed measurement of precipitation and the underestimate of precipitation level, and there is no large false precipitation. (4) In addition, we found that the satellite products in the lake distribution area of the TRHR have serious missed precipitation errors, indicating that the GPM satellite products have the poor detection ability of precipitation near plateau lakes. On the whole, the precipitation inversion accuracy of IMERG (Early and Late) products is higher, which can better detect the occurrence of precipitation events, but the estimation of precipitation level is still not accurate. The precision of precipitation of satellite products near inland lakes on the plateau is poor, so the algorithm improvement of new products needs to be further solved in the future.

Description: In agricultural catchments, hydrological processes are highly linked to particle and nutrient loss and can lead to a degradation of the ecological status of the water. Global warming and land use changes influence the hydrological regime. This effect is especially strong in cold regions. In this study, we used long-term hydrological monitoring data (22–26 years) from small agricultural catchments in Norway. We applied a Mann–Kendall trend and wavelet coherence analysis to detect annual and seasonal changes and to evaluate the coupling between runoff, climate, and water sources. The trend analysis showed a significant increase in the annual and seasonal mean air temperature. In all sites, hydrological changes were more difficult to detect. Discharge increased in autumn and winter, but this trend did not hold for all catchments. We found a strong coherence between discharge and precipitation, between discharge and snow water equivalent and discharge and soil water storage capacity. We detected different hydrological regimes of rain and snow-dominated catchments. The catchments responded differently to changes due to their location and inherent characteristics. Our results highlight the importance of studying local annual and seasonal changes in hydrological regimes to understand the effect of climate and the importance for site-specific management plans.

Description: The effects of long-term natural climate change and human activities on runoff generation mechanism in the middle Yellow River Basin are long-standing concerns. This study analyzed the characteristics of hydro-climatic variables in the meso-scale Tuweihe catchment based on the observed data for the period 1956–2016 and a climate elastic method. The spatial distribution of dominant runoff processes (DRP) following land use changes in case of rainfall was identified. The results show significant decreasing trends in annual runoff, whereas slightly downward trends are identified for annual precipitation and potential evapotranspiration, 1984 is detected as the mutation year of the study period. The average contributions of climate change and human activities to the runoff reduction in the Tuweihe catchment were 33.2% and 66.8%, respectively. In general, the influences of human activities on runoff are applied mostly through the alteration of the catchment characteristics. The dominant runoff processes changes between 1980 and 2015 show significant effects of large-scale soil and water conservation measures in the Tuweihe catchment. We found that Hortonian overland flow (HOF) and fast subsurface flow (SSF1) were the two main processes in 1980 (30.3% and 34.4% respectively), but the proportion of HOF decreased by 9.6% in 2015. The proportions of saturation overland flow (SOF) and SSF have increased to varying degrees, which means that the catchment is more prone to generate subsurface flow processes. Consequently, under similar rainfall conditions, the runoff yield of flood events decreases in the second period.