High Groundwater Level Research Articles

Features of waterproofing of agricultural buildings and structures

High groundwater levels, defects and imperfect drainage systems contribute to the active dampening of stone structures, resulting in their corrosion destruction and accelerated load loss. There are two main sources of capillary pull-up: groundwater level and so-called sprayed water. Analysis of the destruction of stone buildings shows that the major factor in their destruction is the various sources of excessive soaking (up to 50% of buildings) and, as a consequence, salinization. High groundwater levels, defects and imperfect drainage systems contribute to the active dampening of stone structures, resulting in their corrosion destruction and accelerated load loss. There are two main sources of capillary pull-up: ground water and so-called sprayed water. The humidity decreases in the bottom-up direction, as well as from the middle of the wall to its outer surfaces, which means that the capillary suction of water is in effect. Analysis of the destruction of stone buildings shows that the major factor in their destruction is the various sources of excessive soaking (up to 50% of buildings) and, as a consequence, salinization. Waterproofing has a huge impact on the durability, comfort, and cost of operating the facilities. The lack of waterproofing or its destruction, as well as the violation of the wet regime, are the cause of many defects in both individual structures and buildings in general, which require considerable cost. In the case of insulation failure or lack thereof, the soil water seeps through the walls and destroys the plaster and masonry from the outside, and after the capillary movement inside the masonry, reaches the inner layer of the plaster. Depending on the degree of threat, the appropriate type of waterproofing should be used. The quality and durability of the waterproofing layer depend on the strength of the surface preparation. Reliable adhesion to the substrate, solid coating and uniform thickness of the waterproofing coating are ensured by quality alignment, cleaning, drying, priming of the insulated surface, as well as careful preparation and execution of joints, touches and seams. To protect the foundations, walls and columns of agricultural buildings and structures from the capillary rise of moisture, we propose to cut off the inter-wall waterproofing and improve the hydrogeological conditions of the site. Waterproofing materials must comply with European standards and be certified by ISO quality management system.

Failure of an unfilled landfill cell due to an adjacent steep slope and a high groundwater level: A case study

Stability is a factor of vital importance for landfills, during both construction and operation. Slope failures are likely to occur in landfills located in regions with soft soils and a high groundwater table. In this study, the failure of an unfilled landfill cell, located in a typical coastal soft soil area, was explored. The failure was found to be caused by the instability of a continuous slope formed by the unfilled landfill cell and an adjacent construction waste landfill. A series of post-failure field investigations were performed, including cone penetration tests, monitoring of horizontal displacement of the sliding body, and an investigation of the groundwater. Additionally, finite element modeling and limit equilibrium analysis were applied to study the failure mechanism and the factor of safety (FOS), respectively. Both the field investigations and the theoretical analyses indicated that the geometrical configuration and the soft substratum provided the basis for the formation of the sliding surface, while a rise of the groundwater level due to continuous rainfall and poor drainage condition triggered the failure. This case reveals that the stability of landfills in regions with soft soils should be thoroughly assessed, and that appropriate ground treatment is necessary to avoid potential sliding along soft substrata. Furthermore, special attention should be paid to determination of the safe distances to surrounding earth structures, considering the effect of any ground treatment applied.

Alternatif Penambahan Limbah Batu Kapur dan Abu Sekam Padi sebagai Bahan Stabilisasi Tanah di Kecamatan Bangorejo Kabupaten Banyuwangi

Ekspansif land having the nature of flower and dwindle, high level ground water level when the rains and will do chap when dry season. The building can experience barstly of wall and degradation of structure as in area Bangorejo Banyuwangi. So that require to be conducted by stabilization to land by adding density and inactive material, debasing surface, changing ugly land, and also add other material so that happened reaction of chemically or nature to the land.
 In this research is conducted by addition of materials mixture Waste Limestone and Dusty Chaff to the ekspansif land, so that can improve the nature of existing land. Sampel taken away from Bangorejo Sub-Province Banyuwangi which consist of 15 dried land example with each composition 3 example to 5 treatment phase.
 Result of data analysis show the existence of repair of land characteristic, that is water rate, specific gravity, liquid boundary, plastis boundary and plasticity index of land go down, so that yield low add-dwindle potency of land. At addition mixture of limestone waste 20 % and dusty chaff of paddy 5 % obtaining optimal result, that is yield strength become 0,281 kg/cm2 and energy support of land become 9,378 ton/m2.

Soil N2O Emissions under Different N Rates in an Oil Palm Plantation on Tropical Peatland

(1) Background: Nitrogen (N) fertilization on drained tropical peatland will likely stimulate peat decomposition and mineralization, enhancing N2O emission from the peat soil. (2) Methods: A field experiment was conducted to quantify the N2O emissions from soil in an oil palm plantation (Elaeis guineensis Jacq.) located in a tropical peatland in Sarawak, Malaysia, under different rates of N fertilizers. The study was conducted from January 2010 to December 2013 and resumed from January 2016 to December 2017. Nitrous oxide (N2O) flux was measured every month using a closed chamber method for four different N rates; control—without N (T1), 31.1 kg N ha−1 yr−1 (T2), 62.2 kg N ha−1 yr−1 (T3), and 124.3 kg N ha−1 yr−1 (T4); (3) Results: Application of the N fertilizer significantly increased annual cumulative N2O emissions for T4 only in the years 2010 (p = 0.017), 2011 (p = 0.012), 2012 (p = 0.007), and 2016 (p = 0.048). The highest average annual cumulative N2O emissions were recorded for T4 (41.5 ± 28.7 kg N ha−1 yr−1), followed by T3 (35.1 ± 25.7 kg N ha−1 yr−1), T1 (25.2 ± 17.8 kg N ha−1 yr−1), and T2 (25.1 ± 15.4 kg N ha−1 yr−1), indicating that the N rates of 62.2 kg N ha−1 yr−1 and 124.3 kg N ha−1 yr−1 increased the average annual cumulative N2O emissions by 39% and 65%, respectively, as compared to the control. The N fertilization had no significant effect on annual oil palm yield (p = 0.994). Alternating between low (deeper than −60 cm) and high groundwater level (GWL) (shallower than −60 cm) enhanced nitrification during low GWL, further supplying NO3− for denitrification in the high GWL, and contributing to higher N2O emissions in high GWL. The emissions of N2O ranged from 17 µg N m−2 hr−1 to 2447 µg N m−2 hr−1 and decreased when the water-filled pore space (WFPS) was between 70% and 96%, suggesting the occurrence of complete denitrification. A positive correlation between N2O emissions and NO3− at 70–96% WFPS indicated that denitrification increased with increased NO3− availability. Based on their standardized regression coefficients, the effect of GWL on N2O emissions increased with increased N rate (p < 0.001). Furthermore, it was found that annual oil palm yields negatively correlated with annual N2O emission and NO3− for all treatments. Both nitrification and denitrification increased with increased N availability, making both processes important sources of N2O in oil palm cultivation on tropical peatland.; and (4) Conclusions: To improve understanding of N2O mitigation strategies, further studies should consider plant N uptake on N2O emissions, at least until the completion of the planting.

Evaluation of Ground Anchor Design on Man-made Cut Slope of Cemented Sand: A Case Study

A system of ground anchor and horizontal drain on a steep cut-slope in Bogor, West Java was designed to stabilize the slope below a bridge structure spanning across a river. Due to the difficulties in the construction of the ground anchor, the design of the ground anchor was evaluated and analyzed for its effect on the stability of the slope. The slope is assumed to have three layers of soil consist of sandy clay (medium stiff), sandy silt (hard), sandy silt (medium stiff), and cemented sand gravel. Four scenarios were evaluated to examine the slope stability: initial stage, the addition of horizontal drain, construction of bored piles with horizontal drain, and addition of ground anchor after the construction of bored piles and horizontal drain. Analysis were done with evaluating the Factor of Safety (FS) of the slope. It was found that the addition of horizontal drain played a big part in stabilizing the slope from initial stage (FS = 0.933 to FS = 1.546), whereas the addition of ground anchor and bored piles were not apparent after the addition of horizontal drain (FS = 1.545 and FS = 1.555), indicating that the main problem of the slope was the high groundwater level. Other than the constructed solutions, shortcrete should also be given at the critical slip surface at the top and surface of the slope in order to reduce erosion by run-off water.

Особенности применения композитного армирования в фундаментах малоэтажных зданий

The article identifies the features of the use of composite reinforcement in the pile and strip foundation of a two-story house. When designing the foundations, the complex geological conditions of the construction site were taken into account: a high level of groundwater, their aggressiveness with respect to metal reinforcement (seasonal fluctuation of water supply and water treatment at the time of engineering and geological surveys at a level of 2.8 m); the possibility of landslide processes on the slopes; insufficient knowledge and anisotropy of the properties of the bulk layer, significant thickness of the bulk layer, excluding its removal and replacement. An analytical calculation and a numerical experiment were carried out, the following features of the use of composite reinforcement were established:
 more effective in strip foundations is fiberglass reinforcement, resistant to aggressive influences; ASK is advisable to use only in lightly loaded pile-tape foundations, or with a small pitch of piles due to low rigidity characteristics of ASK. With a significant load on the structures, it is recommended to use combined reinforcement: in areas of pure compression and tension using ASK, and in bending zones - metal reinforcement.

Countermeasures of water and mud inrush disaster in completely weathered granite tunnels: a case study

This paper presents a case study of the countermeasures of water and mud inrush disasters in the Junchang Tunnel in Guangxi, China. This tunnel was constructed in a weathered granite formation, and four serious water and mud inrush disasters occurred during construction. The geological and hydrological conditions are first reviewed to understand their effects on the water and mud inrush disasters. Four potential causes of the serious water and mud inrush disasters in the Junchang Tunnel were proposed, including the poor stability of the completely weathered granite, the high groundwater level and large groundwater flow rate, insufficient pre-reinforcement of the surrounding rock and the disturbances caused by tunnel construction. Water-sealing and ground reinforcement measures were suggested before excavation to improve the stability of the surrounding rock and plug the water outflow channels, and full-face curtain grouting was considered as the first choice. Furthermore, several improvements, including the combined utilization of various grouting materials, supplementary grouting with steel pipes in collapsed boreholes and dynamically optimized grouting methods, were implemented to solve the serious water inflow and collapse problems experienced during the drilling and grouting work. A detailed curtain grouting scheme was proposed and applied in practice. A comprehensive evaluation based on inspection borehole investigations and P–Q–t analysis indicated that the curtain grouting method yielded satisfactory performance in water sealing and ground reinforcement. In addition, the groundwater level and settlement data collected in the field validated the effectiveness of the proposed countermeasures.

Black alder forests (type 91E0* Natura 2000 type E.2.1.9. NHC) in the Plitvice Lakes National Park

The paper presents the first results of monitoring Natura 2000 habitat type 91E0*in the Plitvice Lakes National Park (Croatia). This type is represented in black alder forests (Alnus glutinosa /L./ Gaertn.) on an area of 44 ha. There, following the Braun-Blanquet method (1964), 25 plots were set up and relevés made, with 175 species of higher plant species recorded. Their environmental and sociological features suggest wetland and periodically flooded habitats with high ground water levels throughout the year, hence hygrophytes are decisive for the community structure. In addition, there is a moderate share of mesophilic species that are not present in the wetland black alder forests along the Sava and Drava rivers in the lowland part of northern Croatia. A comparison of black alder forests of the Plitvice Lakes NP with other black alder syntaxa in Croatia (Figure 2, Table 3) demonstrates that, together with other alder stands in the Dinaric region of Croatia, they belong to the group of wetland forests of the alliance Alnion glutinosae. Their differentiating species with regard to other syntaxa of the alliances Alnion glutinosae and Alnion incanae in Croatia are Fraxinus excelsior, Daphne mezereum, Viburnum lantana, Cirsium oleraceum, Crepis paludosa, Equisetum arvense, Paris quadrifolia, Thalictrum aquilegifolium, Valeriana dioica, Veratrum album, Acer pseudoplatanus, Chaerophyllum hirsutum, Lonicera xylosteum, Filipendula ulmaria, Knautia drymeia, Cruciata glabra. In addition, the researched stands in the Plitvice Lakes NP demonstrate individuality with regard to other stands of the Croatian Dinarides through the differentiating species of Phalaris arundinacea, Dactylorhiza maculata, Cirsium arvense, Primula vulgaris, Listera ovata, Carex acutiformis, C. paniculata, Succisa pratensis, Gentiana asclepiadea. Black alder forests in the Plitvice Lakes NP were created by successive processes in non-forest areas after their fall out of use (Figure 1). They grow by watercourses in karst depressions with occasionally stagnant surface water. Here the river courses are slowed down and distanced from the slopes and surrounding massifs, hence zonal forests do not have a dominant influence on the floral composition. The researched forests are classified in the class Alnetea glutinosae Br.-Bl. et Tx. 1943, order Alnetalia glutinosae Tx. 1937, and alliance Alnion glutinosae Malcuit 1929. They exhibit greatest similarity to the Central European association Carici acutiformis-Alnetum glutinosae. However, these results should not be generalized for the entire Dinaric region of Croatia. Detailed studies of black alder forests in the Dinarides are pending and their results will determine their nomenclature and syntaxonomic character.

Grout diffusion in silty fine sand stratum with high groundwater level for tunnel construction

Silty fine sand stratum with a high water groundwater level is a common soil type with poor strength. During tunnel construction and foundation pit excavation, geologic hazards such as water leakage and ground subsidence are very likely if safety preparations are lacking. In this study, we conducted a theoretical analysis of the grouting process in silty fine stratum using a sleeve valve tube; the diffusion behavior of the grout with Bingham fluid characteristics was determined and simulated for different levels of pressure using the discrete element method. Theoretical analysis and numerical calculations were performed to determine the relationships between the grouting pressure, the diffusion radius, and the initial fracture pressure. A good agreement is obtained between the simulation and measured results, demonstrating the feasibility of the proposed theoretical model. The method is used in an actual grouting engineering project and good results are obtained.

Observations of the ground and structural behaviours induced by a deep excavation in loose sands

Large-scale deep basement excavations are commonly used in metropolitan areas; however, previous studies focused primarily on excavations in impermeable clay instead of permeable sand with high groundwater levels. In this study, a unique opportunity provides a complete picture of the ground and structural behaviours induced by deep excavations in loose to medium sand, which have been rarely studied in the past. With a maximum excavation depth of 16.8 m, the pit was retained by a 0.9-m-thick and 32-m-deep reinforcement concrete diaphragm wall with 4-level struts. The maximum wall displacement (δvh) reached 56 mm at the end of excavation, and the ratio of δvh to the excavation depth was 0.32%. In contrast, the ratio of the maximum surface settlement to the excavation depth was lower, i.e. only 0.2%. Pumping inside the excavation site did not appear to induce a significant impact outside the excavation site due to the retaining wall embedded in a layer of impermeable clay at a depth of 28.5–30.5 m. The plain strain ratio from the observed settlement is interpreted; the ratio indicates a difference of 2–39%. This difference may be connected to the soil anisotropy, or the maximum surface settlement at each monitoring section may not be detected. The wide range of the variance might also be connected with the small measured surface settlements and the difficulty of detecting such small displacements on the ground level in field surveys.

PROBLEMS AND WATER-ECOLOGICAL RISKS OF SITE DEVELOPMENT ON THE DRAINED LANDS OF AN OLD FLOODPLAIN OF THE DNIEPER RIVER

Relevance of research. In recent years, in Ukraine, the development of re-cultivated drained lands takes place, in particular, in the floodplains of the rivers. In the process of construction, drainage systems designed to protect agricultural land and adjoining areas against flooding are often disrupted. In addition, peat and silt deposits may be spread in the floodplain areas, which considerably complicate the construction. The transformation of agricultural drained lands of floodplains in the built-up areas is also associated with an increased risk of flooding, contamination of surface and groundwater, and requires compliance with environmental, water and land legislation. In this regard, an important issue is the study of water and environmental problems connected to the build-up of the land of reclamation systems in floodplains of rivers.
 The purpose of research - to identify possible water and ecological impacts and restrictions as to the development of drained lands within an floodplain of the Dnieper River.
 Objectives of the research - to analyze the available information on the geomorphological, hydrological and hydrogeological conditions of the floodplain territory; to evaluate the condition of the drainage system at the perspective site development; to determine possible changes in the water regime of the floodplain area in the zone of development impact; to evaluate the soil and ameliorate conditions of the territory with regard to its possible use for development and the compliance of the planned design solutions with the requirements of land and water legislation.
 Research methods. Generalization and systematic analysis of the information on the natural conditions of the territory and drainage system operation, carrying out of a reconnaissance survey of the drainage system specifying with the use of temporary well holes the peat deposit thickness, depths of groundwater, water level in reclamation canals and their current state, the implementation of field geodetic works, normative assessment of soil and ameliorative as well as engineering and geological conditions of the site as to its for development.
 Research results. The features of the current environmental and ameliorative situation regarding the possible obstacles to the housing complex construction and its further functioning, the likely or inevitable negative consequences of the floodplain development were determined. It was established that the existence of closed depressions in the microrelief against the background of the general low draining capacity of the floodplain territory, in case of extremely heavy rainfall, may cause the accumulation of surface runoff in the depressions and territory flooding. High groundwater level, deterioration of draining capacity, destruction of drainage drains during the construction will lead to the proliferation and intensification of man-made flooding processes in poorly-drained areas.
 One of the most complicating factors in the construction of the site is the wide spread of peat deposits, peat soils, silt, which, according to the general engineering and geological classification, are “weak” soils characterized by low bearing properties and can not be recommended as a basis for the foundations of ground structures and buildings. It has been determined that the existing “Shaparnya” drainage system is in unsatisfactory technical condition, and its parameters (rather low depth of drainage canal laying and a large distance between them) make it impossible to achieve the normative depths of groundwater for built-up areas.
 Conclusions. The area of ​​weakly drained floodplain of the Dnieper River can be differentiated into weakly favorable and unfavorable parts for the construction of the territory, and the main complicating factors for the construction are the spread of peat deposits and peat soils, frequent underflooding of the territory and the risk of its flooding in a case of abnormal heavy high rainfall. The proper protection of the territory of residential development against underflooding and flooding should include the reconstruction of the drainage system, artificial increase of planning ground levels and ensuring the safe functioning of the existing at the site water body.

Degradation and Mobility of Pesticides in Norwegian Soils

Degradation and Mobility of Pesticides in Norwegian Soils

Conjugacy of two types of phenotypic variability of small-leaved linden

The properties of five bilaterally symmetrical features of the leaf blades of the small-leaved linden (Tilia cordata Mill.) in four populations of the Moscow Region in 2014–2017 were studied. The angle trait was excluded, because it possessed the property of directional asymmetry. Instead, a new linear trait was used: the distance between the base of the second vein of the first order and the base of the first vein of the second order on the first vein of the first order. The population difference in fluctuating asymmetry (FA) was found only in the first two traits (leaf width and distance between the bases of the first vein of the first order and the second vein of the second order). The largest value of FA was in the urban environment, the smallest was in the rural areas. A weak negative correlation was obtained between the magnitude of linear characteristics and the value of FA, as well as a weak positive correlation relationship between the values of FA in five traits. The first trait had the highest fluctuation variability, and the second one had the highest plastic variability. The regression dependence of the fluctuation variability on the plastic variability (b1 = 0.25, p <0.05) and the dependence of these two types of variability on the interaction of the factors “year” and “site of sampling” were revealed. Thus, the conclusion was made about the conjugacy of two types of variability: fluctuation and plastic. According to the authors, asynchronous growth, competition for light in conditions of high solar activity in 2014–2016 compared to the abnormal wet summer of 2017 led to an increase in FA due to destabilization of mechanisms of growth and regulation of gene expression, which contributed to a decrease in the stability of development. The increase in FA and the decrease in the developmental stability in urban ambient in 2016 could be due to: a)an intensive flow of vehicles in spring and summer, b) a high level of groundwater in this part of the city and c) increased hydrolytic acidity of the soil.

Repairing earth dam drainage systems

Introduction: when reconstructing or overhauling dams, great attention should be paid to drainage systems as the most critical components of the installations. The article describes the typical malfunctions of earth dam pipe drainages. The research considers geological and hydrogeological features that were not taken into account when developing projects.
 Materials and methods: control and measuring instrumentation (piezometer network), full-scale experiments on disabling pipe drainage and mathematical modelling were used as the filtration regime research methods.
 Results: analysis of the hydrogeological features of the base of the right-bank floodplain dam of the Nizhegorodskaya hydroelectric power plant and field filtration observations revealed a strong drainage effect of the base on the filtration flow at several areas of the dam body. At the other areas, a high groundwater level position at the dam downstream and its outlet into the pipe drainage at the downstream were recorded. Substantiated by filtration calculations, the proposed repair of the drainage system consisted in designing open drainage along the dam axis and backfilling the territory at the downstream by 2.0 m that excludes impoundment of the territory without the pipe drainage.
 Conclusions: the following engineering solutions can be recommended for repairing earth dam drainage systems: construction of backfill drainage trenches in the dam downstream, new pipe drainage at higher elevations or an open drainage channel in solid reinforced concrete arranged along the axis of the dam. The proposed version of the pipe drainage repair provides for constructing an open drainage channel in solid reinforced concrete on a reverse filter with an arrangement of gravel-filled asbestos-cement pipes in the dam slopes and bottom. Such a design solution allows repairing the drainage system without dewatering and, if necessary, completely refusing the existing pipe drainage.

Design and construction of the new library at China Agricultural University

A new, world-class library has been built at China Agricultural University in Beijing, the oldest agricultural higher education institute in China. The new building’s attractive natural stone facades reflect both old and new, from bamboo writing slips to barcodes, while the dramatic internal space is user-friendly, energy-efficient and flexible. During construction, an innovative hybrid diaphragm walling solution was adopted due to the high groundwater level and restricted site. Building information modelling technology was also successfully used throughout design and construction, helping to improve construction quality and safety management.

Estimation of hydraulic parameters from pumping tests in a multiaquifer system

The hydrogeologic conditions in Tianjin, China, are characterized by a system of multiple alternating aquifers and aquitards and a high groundwater level. Generally, the groundwater system to a depth of 70 m includes one phreatic aquifer and three semiconfined aquifers (AqI–AqIII). The distribution of aquifers varies greatly. Accurate estimates of aquifer parameters from pumping tests are essential in geotechnical engineering practice. In this study, the applicability of different models for estimating hydraulic parameters in a multiaquifer system is analyzed. To avoid errors in the graphic-analytical process and to enhance the efficiency and accuracy, a hybrid algorithm, called GALMA (a genetic algorithm (GA) combined with the Levenberg–Marquardt (LM) algorithm), is used with the Neuman and Witherspoon model and ratio method. The estimated values in the second and third semiconfined aquifers (AqII and AqIII) from various solutions are compared with the measured data. Further validations based on the prediction of the drawdown values are performed via a three dimensional numerical simulation.

Downscaling GRACE TWSA Data into High-Resolution Groundwater Level Anomaly Using Machine Learning-Based Models in a Glacial Aquifer System

With continued threat from climate change and human impacts, high-resolution and continuous hydrologic data accessibility has a paramount importance for predicting trends and availability of water resources. This study presents a novel machine learning (ML)-based downscaling algorithm that produces a high spatial resolution groundwater level anomaly (GWLA) from the Gravity Recovery and Climate Experiment (GRACE) data by utilizing the relationship between Terrestrial Water Storage Anomaly (TWSA) from GRACE and other land surface and hydro-climatic variables (e.g., vegetation coverage, land surface temperature, precipitation, streamflow, and in-situ groundwater level data). The predicted downscaled GWLA data were tested using monthly in-situ groundwater level observations. Of the 32 groundwater monitoring wells available in the study site, 21 wells were used to develop the ML-based downscaling model, while the remaining 11 wells were used to assess the performance of the ML-based downscaling model. The test results showed that the model satisfactorily reproduces the spatial and temporal variation of the GWLA in the area, with acceptable correlation coefficient and Nash-Sutcliffe Efficiency values of ~0.76 and ~0.45, respectively. GRACE TWSA was the most influential predictor variable in the models, followed by stream discharge and soil moisture storage. Though model limitations and uncertainty could exist due to high spatial heterogeneity of the geologic materials and omission of human impact (e.g., abstraction), the significance of the result is undeniable, particularly in areas where in-situ well measurements are sparse.

Hydrological impact of a reservoir network in the upper Gan River Basin, China

AbstractA few relatively large reservoirs, hundreds of small reservoirs, and numerous farm dams were built in the upper Gan River Basin, China. The operation of such a reservoir network can serve as a significant source of variability in the local hydrological regime and should be included in research to better understand the interaction between multiple hydrological processes and watershed management. In this study, a reservoir network module that included reservoirs of multiple sizes was developed and fully integrated into the coupled land surface and distributed hydrologic model system (CLHMS), for a detailed description of the hydrological impact of a reservoir network. A generalized release scheme was employed to determine the outflow of both large and small reservoirs. The integrated model was then evaluated against observations and reanalysis data, which indicate that the model can reasonably reconstruct the reservoir operation, streamflow, and other hydrological variables. Results quantitatively demonstrate that a reservoir network can result in an increased streamflow in dry seasons, a decreased streamflow in wet seasons, a generally larger groundwater discharge, higher groundwater level, a slightly damper soil condition, and a larger amount of evapotranspiration at the basin level. With the integrated model, it is feasible to achieve more sustainable watershed planning and management.

Vegetation composition of Lolium perenne-dominated grasslands under organic and conventional farming

Agricultural intensification has caused a decline of semi-natural grasslands and loss of botanical diversity, making agricultural fields dominated by Lolium perenne the main grassland system in large areas of Europe. Increased insight into the factors determining their vegetation composition and plant species richness is needed to improve the effectiveness of agri-environment schemes and to substantiate the benefits of organic over conventional agriculture. Our aims were (1) to determine the difference in vegetation composition (including species richness) between Lolium perenne-dominated fields of conventional and organic farms in a case study region in The Netherlands, and (2) to identify the soil and management related drivers behind this difference.We collected vegetation, soil and management data in grasslands of dairy farms under conventional or organic management (45 fields in total), and used multivariate statistics to determine the effect of fertilisation rates, grazing and cutting regime, and soil properties on plant species composition. In a next step we determined to what extent these abiotic drivers differ between organic and conventional farms.On average the organic fields appeared to have a c. 30% higher plant species richness compared to the conventional ones. Vegetation composition was most strongly influenced by groundwater level and nitrogen and phosphorus fertilisation rates, and to a lesser extent by plant-available soil potassium, mowing date, total soil nitrogen, potassium fertilisation rate, age of each field, and livestock (cow or sheep). In general, a low fertilisation rate, high groundwater level, late mowing, low level of plant-available potassium, high level of total soil nitrogen, old fields and the presence of sheep promote a high species richness. However, of these variables only nitrogen fertilisation rate and groundwater level differ significantly between the organic and conventional farms and are therefore likely to be the abiotic drivers of the difference in species richness and vegetation composition between the farm types. Of these two, the difference in nitrogen fertilisation rate is a direct result of a difference in management philosophy, but the difference in groundwater level is not. We hypothesize that the latter difference is caused by economic drivers, whereby a less productive soil is an incentive for a changeover to organic farming. If this is the case indeed, the application of agri-environment schemes would be most effective in less productive (and naturally more species-rich) sites.

Immediate and lag effects of hydrological change on floodplain grassland plants

Hydrological alteration due to climate change events such as floods and drought is a significant threat to globally important wetlands, including floodplain wet grasslands. This research incorporated two field experiments with the aim to assess immediate and longer-term functional responses of floodplain plants to hydrological change. Plant introductions and transplants between a wetter riparian and a drier site in southern England were used to simulate hydrological change. Species showed immediate and differential responses to contrasting hydrologies. Rhinanthus minor, a hemi-parasitic annual species with ruderal traits, was lost from the riparian grassland within four weeks. The survival and production of a leguminous perennial, Lathyrus pratensis, in high groundwater levels soon decreased. However, the perennial Primula veris mostly functioned well in contrasting hydrological regimes, possibly because it can tolerate stress. The perennial wetland species Caltha palustris showed lag effects, over three years, when its hydrology was altered to a sub-optimal drier scenario by transplantation, with declining survival and a sustained reduction in leaf production and flowering. Disturbance caused by transplantation and weather conditions also affected its performance. Thus, this study shows that some functionally important floodplain species may succumb within weeks to a hydrological event facilitated by climate change, unless they are able to tolerate the challenging conditions, while the performance of other characteristic species could decline and continue to show constrained performance for years as a consequence of altered hydrology.