Spatial Model Assessment of P Transport from Soils to Waterways in an Eastern Mediterranean Watershed

Abstract

P index is a management tool commonly used to identify critical source areas (CSAs) in agro-catchments. We tested the applicability of several P-index models adjusted to Eastern Mediterranean conditions. On the basis of model structure and data requirements, we selected the Arkansas model and two models with the RUSLE equation and runoff curve number (RCN). Concurrently, we developed a GIS-based Hermon-P model which was designed to simulate rainfall-runoff events representing the major nutrient-transport mechanism in Eastern Mediterranean. The P index values computed by the Arkansas and RUSLE models exhibited low correlation (r 2 < 0.32) with the measured soluble reactive (SRP) and total P (TP), while the RCN model result correlations were somewhat higher (r 2 = 0.53 for SRP and 0.45 for TP). High correlations between the calculated and measured P during rainfall-runoff events were only achieved with the Hermon model (r 2 = 0.77 to 0.9). These high coefficients resulted from avoiding subjective categorization of the continuous variables and using the measured site-specific erosional predictors instead. On one occasion, during the first significant runoff event of the year, the Hermon model failed to predict total P in the stream water (r 2 = 0.14) because of considerable resuspension of stream sediments. Most of the P-index models are based on the perceptual transfer-continuum framework that was developed for temperate agro-catchments; this framework does not consider P resuspension along streams during OPEN ACCESSWater 2013, 5 263 rainfall-runoff events. Hence, a new set of equations should be added to the P index to account for potential resuspension in Eastern Mediterranean streams at the beginning of the hydrological year.

Estimación del factor de transporte del índice de fósforo con climatologías y escenarios de cambio climático en tierras de Jalisco, México

“…Este proceso se identifica en los valores de riesgo medio y alto del escenario RCP4.5 y climatologías estudiadas, asociados principalmente a las tierras con cercanía a las redes de drenaje o cuerpos de agua. Este resultado coincide con otros estudios realizados en escala de cuenca (40,41,42) . Por esta razón, el valor de vulnerabilidad por FTIP actual con respecto al escenario RCP 4.5 en las climatologías evaluadas no refleja grandes cambios, ya que las cantidades de lluvia estimadas para Jalisco en las climatologías futuras no se esperan incrementos importantes o inclusive, en algunas áreas la lluvia se reduce provocando una disminución de riesgo del FTIP en los niveles muy bajo y medio, agregándose esta superficie en el nivel de riesgo bajo que tiende a aumentar.…”

Climate Change Controls Phosphorus Transport from the Watershed into Lake Kinneret (Israel)

“…In dry seasons RT shortens and water exchange level declines when Phophsphorus mass is retained.. Two environmental ecosystems have an impact on P concentration in the Agmon-Hula waters: 1) the Lake itself with submerged plants and chemo-physical processes (sedimentation, phosphorus cycling, etc.) (Gophen 2000; Gophen et al 2001; Symhayov et al 2013); and 2) peat organic soil and water (precipitation, irrigation) flushing (Yatom and Rabinovich 1999; Yatom et al 1996; Litaor et al 2013, 2014; Haygarth et al 2013; Reichman et al 2013). Plant-mediated phosphorus and geo-chemical processes in the peat soil have a major impact on the lake ecosystem, with the first dominant in summer and the second in winter.Considering that plant-mediated phosphorus has a major impact on the lake ecosystem and geo-chemical processes inside the Peat soil as dominant, the domination of the first occur in summer and that of the second in winter.…”

“…Later on, as a consequence of inundation due to water level fluctuation, P availability along the narrow beach stripe increased and Typha vegetation was renewed. The organic peat soil in the Hula Valley is a P-rich habitat (Litaor et al 2013, 2014; Reichman et al 2013; Haygarth et al 2013). Nevertheless, there is a storage of 22–37 and 11–22 tons of P in the upper two 5-cm layers, respectively, in the Agmon-Hula bottom sediments (Gophen 2000).…”

“…Phosphorus, manganese, and organic matter relations in the Hula Valley peat soil have been widely studied (Gophen et al 2014; Haygarth et al 2013; Litaor et al 2013; 2014; Reichman et al 2013; 2016; Yatom and Rabinovich 1999; Yatom et al1996;Xiang et al 1996; Barnea 2009). The impact of geochemical parameters of pH, oxidation–reduction (redox), wettability (rainfall, irrigation), soil properties, temperature, and agricultural management (fertilization) conditions on the dynamics of phosphorus and peat soil particle bound–release relations had been thoroughly investigated in those studies.…”

“…Moreover, plant-mediated phosphorus and its role in the Phosphorus transport from altered wetland soils into water pathways has been documented as well (Gophen 2000; Simhayov et al 2013). External sources of phosphorus in dust deposition and agricultural fertilization have been studied (Foner et al 2009; Litaor et al 2013; Barnea 2009; Reichman et al 2013). Phosphorus supply into the Hula ecosystem by the winter migrators cranes (Grus grus) fed by corn seeds has also been documented (Gophen 2017).…”