Search results for "hydrology"
showing 10 items of 1041 documents
Latvijas ūdeņu vides pētījumi un aizsardzība: LU Bioloģijas fakultātes Hidrobioloģijas katedras sekcijas referātu tēžu krājums (Rīga, 2012. gada 24. …
2012
Krājumā ievietotās LU 70.konferences LU Bioloģijas fakultātes Hidrobioloģijas katedras sekcijas referātu tēzes nav recenzētas.
Testing a Simplified Approach to Determine Field Saturated Soil Hydraulic Conductivity
2013
Abstract Interpreting and simulating hydrological processes need a large number of field saturated soil hydraulic conductivity, Kfs , data that should be collected with simple and rapid field experiments. A Simplified method based on a Beerkan Infiltration run (SBI method) was recently developed and tested successfully on Burundian soils. With the SBI method, a cylinder is inserted to a short depth into the soil and the infiltration time of a few small volumes of water repeatedly applied at the surface of the confined soil is measured. Calculating Kfs needs the slope of the linearized cumulative infiltration vs. time relationship and an estimate of the so called α* parameter. In this invest…
The biocenotic value of Slitere National Park, Latvia, with special reference to inter-dune mires
2019
Inter-dune wetlands in Europe harbour many Red List species because they are very nutrient-poor ecosystems. Most of these wetlands are geologically very young and no or little peat formation has occurred. In Slītere National Park the numerous inter-dune wetlands are relatively old, up to 4500 years old, and most mire communities are peat forming and they are well preserved. However, the hydrological systems that have conserved the mires are largely unknown. In the present study we analysed 128 vegetation relevées of dune mires in order to assess the variation in ecological mire types. We also carried out several short-time studies to get an insight into the peat development and hydrological…
Dynamics of particulate major and trace elements in the lower reaches of the Daugava River and adjacent area of the Gulf of Riga (Baltic Sea).
2004
Suspended particulate matter (SPM) was collected in the freshwater-seawater mixing zone in the lower reaches of the Daugava River (Latvia) and adjacent marine area, during five cruises in 1998-2001. The study focused on biogeochemical phase exchange processes. SPM in the freshwater was found to be mainly allochthonous with a high content of organic matter, Mn and sorbed phosphate. Property-salinity plots suggested flocculation of humic-Fe complexes across the salinity gradient. The variability of sorbed phosphate was related to particulate Fe, although no dependence on pH and ionic strength was observed. The Mn contents of SPM mainly follow conservative mixing, but there are also indication…
Determining short-term changes in the hydraulic properties of a sandy-loam soil by a three-run infiltration experiment
2020
Soil structure-dependent parameters can vary rapidly as a consequence of perturbing events such as intense rainfall. Investigating their short-term changes is therefore essential to understand the general behaviour of a porous medium. The aim of this study is to gain insight into the effects of wetting, perturbation and recovery processes through different sequences of Beerkan infiltration experiments performed on a sandy-loam soil. Two different three-run infiltration experiments (LHL and LLL) were carried out by pouring water at low (L, non-perturbing) and high (H, perturbing) heights above the soil surface and at short time intervals (hours, days). The results demonstrate that the propos…
Water transmission properties of a sandy-loam soil estimated with Beerkan runs differing by the infiltration time criterion
2021
Abstract The Beerkan method consists of a ponded infiltration experiment from a single ring inserted a small depth into the soil. Fixed, small volumes of water are repeatedly poured into the ring to maintain a quasi-zero head on the soil surface. According to the standard Beerkan infiltration run, a new water volume is poured on the infiltration surface when the previously applied volume has completely infiltrated and the soil surface is entirely exposed to air (ta criterion). However, water could also be applied when the soil exposition to air begins (to criterion) or half the soil surface is exposed to air (tm criterion). The effect of the infiltration time criterion on determination of t…
Water balance and pollutant removal efficiency when considering evapotranspiration in a pilot-scale horizontal subsurface flow constructed wetland in…
2016
Abstract In constructed wetland systems (CWs) for wastewater treatment, the performance of the system is affected by evapotranspiration (ET). This study shows the results of a series of water balance and pollutant removal efficiency analyses taken from a pilot horizontal-subsurface flow system (HSSFs) in the West of Sicily (Italy). The system comprised three separate units, one planted with Cyperus alternifolius L., one planted with Typha latifolia L. and an unplanted unit. The system was fed with urban wastewater from an activated-sludge wastewater treatment plant. The aims of the study were to determine water balance and pollutant removal rates when considering evapotranspiration in two r…
Management of Arfak Rainbow Fish Based on Bioecologycal Aspect (Case in Some River in Manokwari)
2018
The aim of this research is to study the bioecological aspect of Arfak Rainbowfish, distribution long-wieght frequency and management of endemic arfak rainbow fish in Manokwari. This study conducted for five months from 7 September 2015 to 9 Januari 2016. Fish sample were collected from Prafi river, Nimbai river and Aimasi river and brought to fisheries laboratory. The method of this research is descriptive methode with field observation. The result of water quality parameters are temperature average 30.01oC±1,06oC, flow rate is slow 0.92±0,12, the pH 7,80±0,12, oxygen solute 5,38±0,24, average biological oxygen demand for Prafi river 4 mg/L, Nimbai river 3.1 mg/L, Aimasi river 5.2 mg/L and…
Impact of hydrologically driven hillslope erosion and landslide occurrence on soil organic carbon dynamics in tropical watersheds
2016
The dynamics of soil organic carbon (SOC) in tropical forests play an important role in the global carbon (C) cycle. Past attempts to quantify the net C exchange with the atmosphere in regional and global budgets do not systematically account for dynamic feedbacks among linked hydrological, geomorphological, and biogeochemical processes, which control the fate of SOC. Here we quantify effects of geomorphic perturbations on SOC oxidation and accumulation in two adjacent wet tropical forest watersheds underlain by contrasting lithology (volcaniclastic rock and quartz diorite) in the Luquillo Critical Zone Observatory. This study uses the spatially-explicit and physically-based model of SOC dy…
Relationships between soil water repellency and microbial community composition under different plant species in a Mediterranean semiarid forest
2014
Abstract Soil water repellency (SWR) can influence many hydrological soil properties, including water infiltration, uneven moisture distribution or water retention. In the current study we investigated how variable SWR persistence in the field is related to the soil microbial community under different plant species (P. halepensis, Q. rotundifolia, C. albidus and R. officinalis) in a Mediterranean forest. The soil microbial community was determined through phospholipid fatty acids (PLFA). The relationships between microbiological community structure and the soil properties pH, Glomalin Related Soil Protein (GRSP) and soil organic matter (SOM) content were also studied. Different statistical …