Aeolian activity in a Urewera catchment

Analyses of sedimentary deposits on the Otapora flat and adjacent flood plain areas of Whakatane River demonstrate that aeolian activity is important even in a humid (BB'r) forested Catchment. The importance of relief and wind conditions are shown. A tentative assessment of potential feral pest damage and increased sheetwash from a forested Urewera catchment is advanced

Modelling the inorganic nitrogen behaviour in a small Mediterranean forested catchment, Fuirosos (Catalonia)

The aim of this work was to couple a nitrogen (N) sub-model to already existent hydrological lumped (LU4-N) and semi-distributed (LU4-R-N and SD4-R-N) conceptual models, to improve our understanding of the factors and processes controlling nitrogen cycling and losses in Mediterranean catchments. The N model adopted provides a simplified conceptualization of the soil nitrogen cycle considering mineralization, nitrification, immobilization, denitrification, plant uptake, and ammonium adsorption/desorption. It also includes nitrification and denitrification in the shallow perched aquifer. We included a soil moisture threshold for all the considered soil biological processes. The results suggested that all the nitrogen processes were highly influenced by the rain episodes and that soil microbial processes occurred in pulses stimulated by soil moisture increasing after rain. Our simulation highlighted the riparian zone as a possible source of nitrate, especially after the summer drought period, but it can also act as an important sink of nitrate due to denitrification, in particular during the wettest period of the year. The riparian zone was a key element to simulate the catchment nitrate behaviour. The lumped LU4-N model (which does not include the riparian zone) could not be validated, while both the semi-distributed LU4-R-N and SD4-R-N model (which include the riparian zone) gave satisfactory results for the calibration process and acceptable results for the temporal validation process

Seasonal differences in runoff between forested and non-forested catchments: a case study in the Spanish Pyrenees

[EN] The hydrological response of two neighbouring catchments in the central Spanish Pyrenees with similar lithology and topography but different land use was compared. One catchment (2.84 km 2 ) was extensively cultivated in the past, and the other (0.92 km 2 ) is covered by dense natural forest. Differences in runoff were strongly related to catchment wetness conditions and showed a marked seasonality: under dry conditions runoff tended to be greater in the former agricultural catchment, whereas under wet conditions it tended to be greater in the forested catchment. One explanation for this switching behaviour could be an increase in the hydrological connectivity within the slopes of the forested catchment as it becomes wetter, which favours the release of large amounts of subsurface flow. Differences in land use (vegetation and soil properties) dictate the contrasting dominant runoff generation processes operating in each catchment, and consequently the differences between their hydrological responses. Key words water yield; seasonal controls; hydrograph characteristics; forestSupport for this research was provided by the following projects: PROBASE (CGL2006-11619/HID), RespHiMed (CGL2010-18374) and MONTES (CSD2008-00040), financed by the Spanish Commission of Science and Technology; ACQWA (FP7-ENV-2007-1), financed by the European Commission; and PI032/08, financed by the Aragón Regional Government. The authors also acknowledge support from RESEL (the Spanish Ministry of the Environment). N. Lana-Renault was the recipient of a research contract (Juan de la Cierva programme) and J. Latron the recipient of a research contract (Ramón y Cajal programme), both funded by the Spanish Ministry of Sciences and Innovation.Peer Reviewe

Landscape-Scale Disturbance: Insights into the Complexity of Catchment Hydrology in the Mountaintop Removal Mining Region of the Eastern United States

: Few land disturbances impact watersheds at the scale and extent of mountaintop removal mining (MTM). This practice removes forests, soils and bedrock to gain access to underground coal that results in likely permanent and wholesale changes that impact catchment hydrology, geochemistry and ecosystem health. MTM is the dominant driver of land cover changes in the central Appalachian Mountains region of the United States, converting forests to mine lands and burying headwater streams. Despite its dominance on the landscape, determining the hydrological impacts of MTM is complicated by underground coal mines that significantly alter groundwater hydrology. To provide insight into how coal mining impacts headwater catchments, we compared the hydrologic responses of an MTM and forested catchment using event rainfall-runoff analysis, modeling and isotopic approaches. Despite similar rainfall characteristics, hydrology in the two catchments differed in significant ways, but both catchments demonstrated threshold-mediated hydrologic behavior that was attributed to transient storage and the release of runoff from underground mines. Results suggest that underground mines are important controls for runoff generation in both obviously disturbed and seemingly undisturbed catchments and interact in uncertain ways with disturbance from MTM. This paper summarizes our results and demonstrates the complexity of catchment hydrology in the MTM region

Economic Impacts of Logging Intensities in the Muda-Pedu Forested Catchment, Kedah, Malaysia

This study was conducted primarily to determine benefits associated with logging and to quantify the cost associated with sedimentation in the Muda and Pedu Forested Catchments, Kedah. Data on timber value were obtained form the Ulu Muda experimental site and those on the rate of sediment yield were obtained from a study by Lai et al. (1999). The estimated NPV of timber under conventional logging (CL) and modified logging (ML) were RM 119.4 million and RM87.9 million respectively for a land area of 118,673 ha over a two cutting cycles of 30 years each. The average sediment yield in the Muda and Pedu Catchments was estimated to be 77.9 tonne/ha/year under catchment protection (CP), 188 tonne/ha/year under conventional logging (CL) and 115.5 tonne/ha/year under modified logging (ML). Meanwhile, the estimated NPV of treated water production under catchment protection (CP) was RM 128.8 million, under conventional logging (CL) was RM 121.3 million and under modified logging (ML) was RM 125.8 million. The incremental NPV (ML-CP) under modified logging option (ML) was very small valued at RM3.0 million as compared with the conventional logging (CL) with RM7.5 million. The small average incremental NPV under modified logging (ML) was due to the low incremental NPV gained when compared to the conventional logging option. The rise in the sediment concentration caused by CL option was not high enough to cause a high increase in water treatment plant. The above analysis supported conventional logging option over modified logging when only the off-site cost of sedimentation is incorporated This analysis is inconclusive since other physical impacts of logging have not been incorporated such as the potential welfare loss of biodiversity and climate benefits of protected forest. Nevertheless, the analysis has shown that logging does provide off-site cost in the form of higher water treatment costs. This kind information could be useful to policy makers when deciding upon land use options

Quantifying temporal and spatial variations in sediment, nitrogen and phosphorus transport in stream inflows to a large eutrophic lake

High-frequency sampling of two major stream inflows to a large eutrophic lake (Lake Rotorua, New Zealand) was conducted to measure inputs of total suspended sediment (TSS), and fractions of nitrogen and phosphorus (P). A total of 17 rain events were sampled, including three during which both streams were simultaneously monitored to quantify how concentration–discharge (Q) relationships varied between catchments during similar hydrological conditions. Dissolved inorganic nitrogen (DIN) concentrations declined slightly during events, reflecting dilution of groundwater inputs by rainfall, whereas dissolved inorganic P (PO₄–P) concentrations were variable and unrelated to Q, suggesting dynamic sorptive behaviour. Event loads of total nitrogen (TN) were predominantly DIN, which is available for immediate uptake by primary producers, whereas total phosphorus (TP) loads predominantly comprised particulate P (less labile). Positive correlations between Q and concentrations of TP (and to a lesser extent TN) reflected increased particulate nutrient concentrations at high flows. Consequently, load estimates based on hourly Q during storm events and concentrations of routine monthly samples (mostly base flow) under-estimated TN and TP loads by an average of 19% and 40% respectively. Hysteresis with Q was commonly observed and inclusion of hydrological variables that reflect Q history in regression models improved predictions of TN and TP concentrations. Lorenz curves describing the proportions of cumulative load versus cumulative time quantified temporal inequality in loading. In the two study streams, 50% of estimated two-year loads of TN, TP and TSS were transported in 202–207, 76–126 and 1–8 days respectively. This study quantifies how hydrological and landscape factors can interact to influence pollutant flux at the catchment scale and highlights the importance of including storm transfers in lake loading estimates

Autumn Storms Trigger Enhanced Export of Iron, Phosphorus, and Carbon from a Forested Vermont Catchment

Autumn leaf fall may be an important driver of annual stream loading in forested catchments due to the introduction of large amounts of labile organic matter. In light of climate change projections for an intensification of the autumnal hydrological cycle for northern temperate forests, there is an increasing demand to understand this leaf fall period, and the extent to which it may drive water quality. In this study, we examine the export and biogeochemical coupling of dissolved organic carbon (DOC), iron (Fe), aluminum (Al), and phosphorus (P) during autumn and summer storms to understand the effects of seasonality and storm timing and magnitude on stream loading dynamics. We utilize in situ spectrophotometric sensors to measure UV-Vis light absorbance with high temporal resolution in order to quantify rapid changes in stream chemistry during storm events. We also explore the potential to project concentrations of the aforementioned parameters using partial least squares regression (PLSR) and high frequency absorbance data. Post leaf fall autumn storms resulted in the export of 23% of total study DOC in a 2-week period, as well as the largest fluxes of Fe and Al observed over the study period. These results may have important implications for nutrient loading in the receiving water body, Lake Champlain

The prediction of suspended solids of river in forested catchment using artificial neural network

This study presents an artificial neural network (ANN) model that is able to predict suspended solids concentrations in forested catchment namely Berring River, Kelantan, Malaysia.The network was trained using data collected during a period of 13 days in April 2001. The sampling location was established in the middle section of the river for collecting water samples. The study was carried out for a duration of two weeks in April 2001. The water sample was collected at 60% of the total depth from the river bed for every two hours starting from 6:00 am to 12:00 midnight for the whole duration of the study period. In this study five parameters were selected as input parameter for the network which are turbidity, flow velocity, depth, width, and weather condition of during the sampling period, while suspended solids as desire output. The data fed to the neural network were divided into two set: a training set and testing set. 116 of the data were used in training set and 24 remained as testing set. A network of the model was detected automatically by the network to give good predictions for both training and testing data set. A partitioning method of the connection weights of the network was used to study the relative percentage contribution of each of the input variables. It was found that turbidity and river width gives 73.03% and 24.73% each. The performance of the neural network model was measured by computing the correlation coefficient which gives the value of 0.93. It’s shown that the neural network gives superior predictions. Based on the results of this study, ANN modeling appears to be a promising technique for the prediction of suspended solids. Dynamic Metadata(s

The impact of vegetation on fractionation of rare earth elements(REE) during water–rock interaction

Previous studies on waters of a streamlet in the Vosges mountains (eastern France) have shown that Sr and rare earth elements (REE) principally originate from apatite dissolution during weathering. However, stream water REE patterns normalized to apatite are still depleted in light REE (LREE, La–Sm) pointing to the presence of an additional LREE depleting process. Speciation calculations indicate that complexation cannot explain this additional LREE depletion. In contrast, vegetation samples are strongly enriched in LREE compared to water and their Sr and Nd isotopic compositions are comparable with those of apatite and waters. Thus, the preferential LREE uptake by the plants at the root–water–soil (apatite) interface might lead to an additional LREE depletion of the waters in the forested catchment. Mass balance calculations indicate that the yearly LREE uptake by vegetation is comparable with the LREE export by the streamlet and, therefore, might be an important factor controlling the LREE depletion in river waters