Mapping pH of Groundwater and Determination of Vulnerability Areas for Citrus and Rice Growth in Mazandaran

IntroductionMazandaran province is one of the most important rice and citrus-producing areas in Iran, where most of the citrus orchards and agricultural fields are irrigated with groundwater. On the other hand, irrigation water pH is one of the basic qualitative factors that determine the solubility and biological availability of chemical components in the soil such as nutrients and heavy metals, and it can affect agricultural production.Materials and MethodsThe coastal strip of Mazandaran Province toward the southwest of the Caspian Sea is situated in the north of Iran with an area of 8,252 km2 between 35.77 to 36.99 N latitudes and 50.36 to 57.13 E longitudes. In this study, the temporal and spatial variations of groundwater salinity were studied in the coastal strip using data from 300 wells, collected by Mazandaran Regional Water Company. Data included mean pH for each 6-month period of 9 consecutive years, from 2012 until the end of 2020. pH maps and maps of the risk probability area for rice and citrus growth were obtained by using Ordinary Kriging (OK) and Indicator Kriging (IK) in ArcGIS 10.7.1 software, respectively. Classifications were selected according to the properties pH range for the growth of citrus (5.8, 8) and the optimum pH for rice (6.8) in OK method. The indicator amount of pH was considered equal to 6.8 in IK method. Thereby, areas belonging to different pH classes were outlined and places with the risk probability for growing the rice and citrus were identified.Results and DiscussionThe 11 different models for semivariograms were drawn, and the best one was chosen according to the lowest nugget-to-sill ratio, and thus Stable and Exponential were obtained as the highest frequency for first and second half-years. The indices of cross validation for each selected semivariogram were estimated within acceptable ranges. In Ik method, the pH of studying area was classified into 4 ranges of 8, and the percentage area of each classification derived from the ArcGIS software, the average area of each classification during the studying period was calculated zero, 0.6, 83.5 and 15.9 percent, respectively. It showed that most part of the study area located in the range of 6.8-8. It means most rice fields and citrus orchards were irrigated by the groundwater with the pH close to neutral. The obtained maps in the OK method indicated that the pH of the groundwater was not acidic in any points and alkaline conditions were observed in the western and eastern parts of the province. Therefore, The IK method was used to further investigate and determine the vulnerable areas. The probability of pH risk in rice and citrus growth was classified into 4 ranges (0-20%, 20-40%, 40-60% and 60-100%), and the average percentage area of each classification along the period was estimated 94.9, 4.8, 0.3 and zero percent, respectively. Using the IK method, higher probability of groundwater pH reducing the yield in citrus orchards and rice fields was found in eastern parts of Mazandaran province, which was about 5% of total studying area. Also, the results of the study in these 9 consecutive years did not show any decreasing or increasing trend in pH changes and consequently the area under each classification.ConclusionGenerally, the results indicated that the pH of groundwater for irrigating the citrus orchards and rice fields was appropriate in the most parts of the province and merely in the eastern part of the province, low water alkalinity may make a risk probability for rice and citrus growth in both western and eastern parts of the province. Due to the fact that alkaline water causes soil alkalinity and consequently reduces the solubility of phosphorus and some other plant nutrients in soil, it is suggested to supply the optimum required fertilization amounts of the nutrients in soil. However, the amount of fertilization should be on the basis of field research results. It is also proposed to study the condition of rice and citrus growth and the irrigated water in more details through the farms of western parts of the province. Due to the fact that most citrus orchards in this province are irrigated under the pressurized irrigation systems and using groundwater for irrigation, it is suggested that the Langelier Saturation Index (LSI) be examined in future research

Experimental Investigation of Local Scouring around a Series of L-Head Groynes

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Estudio de las perspectivas tridimensionales de la estructura de flujo alrededor del pilote del puente en función de la distribución del patrón de vegetación

Modeling techniques have enabled us to understand how to protect vital infrastructures using nature-based solutions. In this research, we demonstrated that by selecting a specific vegetation pattern distribution upstream of the pile as a nature-based solution, we could reduce the amount of scouring around the bridge piles. This is essential to avoid the negative impacts that occur after landslides, flash floods, or mudflows close to populated areas. This solution can mitigate the global problem of bridge failure. To achieve this goal, an Acoustic Doppler Velocimetry device (ADV) was used to measure the velocity components in an experimental channel with a 90 cm width, 15 meters long, and 60 cm high. Two different widths of vegetation were used: the overall vegetation, with a 90 cm width, and the patched one, with a 10 cm width, positioned upstream of the bridge pile. In the case of using patched vegetation, a 36% reduction was observed in the amount of scouring around the bridge pile compared to the free-vegetation case, showing the positive effect of using vegetation to reduce scouring. In both cases, the amount of negative Reynolds shear stresses decreased when the presence of vegetation was registered. Using octant analysis, the overall vegetation was shown to convert internal events into external ones in front of the pile. However, in the case of using patched vegetation, internal events were also observed in addition to external events. Patchy vegetation changed the transverse direction of outward vortices from internal to external. In the presence of patchy vegetation, the dominance of the inward event decreased sharply. The presence of vegetation in the flow path affected some bursting events and, as a result, reduced scouring. The results showed that each of the used vegetation models has a different effect on bursting events, and these events can affect the amount of scouring hole depth.Las técnicas de modelado nos permiten comprender cómo proteger infraestructuras vitales mediante soluciones basadas en la naturaleza. En esta investigación, demostramos que, al seleccionar una distribución específica del patrón de vegetación aguas arriba de un pilote, podríamos reducir la cantidad de socavación alrededor de los pilotes de un puente. Esto es clave para evitar los impactos negativos que ocurren después de los deslizamientos de tierra, las inundaciones repentinas o los flujos de lodo cerca de áreas pobladas. Esta solución puede mitigar la desestabilización de infraestructuras como los puentes. Para lograr este objetivo, se utilizó un dispositivo de Velocimetría Acoustic Doppler (VAD) para medir los componentes de velocidad en un canal experimental de 90 cm de ancho, 15 metros de longitud y 60 cm de altura. Se utilizaron dos anchos diferentes de vegetación: la vegetación en general, con un ancho de 90 cm, y la parcheada, con un ancho de 10 cm, ubicada aguas arriba del pilote del puente. En el caso de usar vegetación parcheada, se observó una reducción del 36% en la cantidad de socavación alrededor del pilote del puente en comparación con la vegetación libre, mostrando el efecto positivo de utilizar vegetación para reducir la socavación. En ambos casos, la cantidad de tensión negativa de Reynolds disminuyó en presencia de vegetación. Mediante un análisis de octantes, se demostró que la vegetación en general convirtió los eventos internos en externos frente a la estructura. Sin embargo, en el caso de utilizar vegetación parcheada, también se observaron eventos internos además externos. En presencia de vegetación irregular cambió la dirección transversal de los vórtices hacia afuera de internos a externos. En presencia de vegetación irregular, la dominancia del evento interno disminuyó bruscamente. La vegetación en la trayectoria del flujo afectó algunos eventos de fractura y, como resultado, redujo la socavación. Los resultados mostraron que cada uno de los modelos de vegetación utilizados tiene un efecto diferente en los eventos de fractura y estos eventos pueden afectar la profundidad del agujero de socavación

Urban Flood-Risk Assessment : Integration of Decision-Making and Machine Learning

Urban flood-risk mapping is an important tool for the mitigation of flooding in view of continuing urbanization and climate change. However, many developing countries lack sufficiently detailed data to produce reliable risk maps with existing methods. Thus, improved methods are needed that can help managers and decision makers to combine existing data with more soft semi-subjective data, such as citizen observations of flood-prone and vulnerable areas in view of existing settlements. Thus, we present an innovative approach using the semi-subjective Analytic Hierarchy Process (AHP), which integrates both subjective and objective assessments, to help organize the problem framework. This approach involves measuring the consistency of decision makers’ judgments, generating pairwise comparisons for choosing a solution, and considering criteria and subcriteria to evaluate possible options. An urban flood-risk map was created according to the vulnerabilities and hazards of different urban areas using classification and regression-tree models, and the map can serve both as a first stage in advancing flood-risk mitigation approaches and in allocating warning and forecasting systems. The findings show that machine-learning methods are efficient in urban flood zoning. Using the city Rasht in Iran, it is shown that distance to rivers, urban drainage density, and distance to vulnerable areas are the most significant parameters that influence flood hazards. Similarly, for urban flood vulnerability, population density, land use, dwelling quality, household income, distance to cultural heritage, and distance to medical centers and hospitals are the most important factors. The integrated technique for both objective and semi-subjective data as outlined in the present study shows credible results that can be obtained without complicated modeling and costly field surveys. The proposed method is especially helpful in areas with little data to describe and display flood hazards to managers and decision makers

Experimental Design of Nature-Based-Solution Considering the Interactions between Submerged Vegetation and Pile Group on the Structure of the River Flow on Sand Beds

Designing correct engineering infrastructures to reduce land degradation processes and considering natural elements to achieve this goal are key to correctly managing potential natural hazards affecting human activities and natural ecosystems. This research investigated the scour depth and velocity vectors around bridge piles with and without upstream vegetation protection. A Doppler velocity meter was used to measure velocity components in a channel 90 cm wide, 16 m long, and 60 cm high. Variable parameters were the number of bridge piles, the height, density, and width of vegetation upstream, as well as the distance between bridge piles. Using a triple pile group with a distance between piles of 10 cm and overall vegetation across the channel, the depth of the scour hole upstream of the first pile decreased by 40% compared to the single pile with no vegetation. This result shows the significant impact of using vegetation and pile groups to reduce scour around piles. Lower vertical velocity gradients, more consistent velocity vectors, reducing the downstream flow range, and restraining horseshoe vortexes and wake vortices were observed in utilizing vegetation. We confirmed that vegetation is an essential factor in changing the flow, transportation of sediment, and conserving ecological services in rivers

Experimental Design of Nature-Based-Solution Considering the Interactions between Submerged Vegetation and Pile Group on the Structure of the River Flow on Sand Beds

Designing correct engineering infrastructures to reduce land degradation processes and considering natural elements to achieve this goal are key to correctly managing potential natural hazards affecting human activities and natural ecosystems. This research investigated the scour depth and velocity vectors around bridge piles with and without upstream vegetation protection. A Doppler velocity meter was used to measure velocity components in a channel 90 cm wide, 16 m long, and 60 cm high. Variable parameters were the number of bridge piles, the height, density, and width of vegetation upstream, as well as the distance between bridge piles. Using a triple pile group with a distance between piles of 10 cm and overall vegetation across the channel, the depth of the scour hole upstream of the first pile decreased by 40% compared to the single pile with no vegetation. This result shows the significant impact of using vegetation and pile groups to reduce scour around piles. Lower vertical velocity gradients, more consistent velocity vectors, reducing the downstream flow range, and restraining horseshoe vortexes and wake vortices were observed in utilizing vegetation. We confirmed that vegetation is an essential factor in changing the flow, transportation of sediment, and conserving ecological services in rivers