Hydrologic Soil Group Research Articles

EMPLOYING MODERN TECHNIQUES IN STUDYING SOIL AND WATER RESOURCES IN SELECTED AREA OF NORTH WESTERN COASTAL REGIONS, EGYPT

The study area is extending from Minqar Alousran at the east to Beer Qaaem at the west, Marsa Matrouh at the north to Jable Khaled at the south. The total studied area is about 345563.52 Fadden. Ninety eight soil profiles were selected representing the geomorphic units. The qualitative approach was used to land evaluation. Hydrological and morphometric characteristics have been obtained. Four main geomorphic units were identified: Coastal Plain, Northern Plateau, Southern Plateau and Lybian Plateau. The soils ranged from very shallow to very deep. The dominant soil texture is between sandy clay loam to sand. These soils are moderately to extremely calcareous. These soils are slightly to strongly alkaline. The studied soils in the geomorphic units are classified as follow: Lithic Haplocalcids, Typic Haplocalcids, Typic Torriorthents, Gypsic Aquisalids, Typic Calcigypsids, Lithic Torriorthents and Oxyaquic Torripsamments. Land evaluation for the studied soils. The study aimed also to predict annual peak flow and runoff water volume, as well as the 20, 10, 5, 3, and 2year return periods. Results referred that El-Hraka basin characterized by an area of 178.31km2, basin length of 33.70 km, perimeter of 132.8 km, and gentle slope of 0.012 m/m. There are four types of land use/land cover in the study basin named: agriculture land, bare land, rocky areas and urban representing 3.45, 92.98, 3.41 and 0.16% of El Hraka basin, respectively. There are two hydrologic soil group of the study basin A and C depending on the soil texture. The Curve Number (CN) depending on the land use / land cover and the hydrologic soil groups. Its average values are 73.67 for El-Hraka basin. The annual runoff water volumes are 10583.29 m3 that recharge the groundwater reservoir. However, the annual infiltration volumes are 8195.01m3. The peak flow of the 20, 10, 5, 3 and 2 year return periods flash flood is 29.24, 17.98, 9.50, 3.78 and 0.75 m3/s respectively. The runoff volume of the 20, 10, 5, 3 and 2 year return-periods is 2.78 million, 1.71 million, 906,578.6, 359,883and 69,989.4 m3 respectively for the study basin.

HYPSOMETRIC ANALYSIS OF AL-ADHAIM BASIN USING A NEW GIS- TECHNIQUE

Al-Adhaim dam basin is extended across the boundaries of Salahuddin, Kirkuk, and Sulaymaniyah provinces in the northern part of Iraq, covering an area of 11831 km2. The area is covered mainly in most upperparts by sedimentary rocks of the lower Eocene to Pliocene ages. The lower parts are occupied by sheet runoff deposits from the Quaternary age. The objectives of the current study are to carry out detailed measurements of hypsometric parameters to evaluate the degree of erosion conditions and to show the essential factors controlling the development of geomorphic stages in different parts of the basin. The analysis was carried out based on ASTER GDEM data using ArcGIS v10.6 hydrology toolbox and the morphometric toolbox and dividing the basin into fifteen sub-basins. The results show that the Al-Adhaim basin passes in the monadnock phase with a hypsometric integral of 19.02% and a highly concaved hypsometric curve. The sub-basins are classified into two groups of geomorphic stages, i.e., mature stage and Monadnock stage with hypsometric integral values between 18.4% and 34.6%. The results reveal the basin was controlled mainly by slopes, lineaments, Tertiary outcrops, Quaternary deposits, and hydrological soil groups B and D.

Estimation of Surface Runoff in an Ungauged Basin Using SCS-CN Method, A Case Study of Manair River Basin in Telangana, India

The present research work was carried out for estimation of surface runoff in an ungauged basin by SCS-CN curve method. Satellite Images, digital elevation model data, hydrological Soil Data and precipitation data combined with Geo spatial technologies was used for land use/land cover classification, drainage extraction, basin delineation and for the surface runoff estimation of the study area. The study area Manair basin is located under 4 districts Karimnagar, Kamareddy, Medak and Rajanna-Siricilla districts of Telangana State, Southern India. Maniar River is one of the major tributary to the Godavari River. The Manair Basin is further divided into three sub basins in which three dams named Upper Maniar dam, Mid Manair dam and Lower Manair dam are there across the Manair river basin. In the present study the surface runoff estimation is computed for the entire Manair basin. The total drainage area of basin is 6668.212 sq. km and morphometric analysis shows sub-dendritric and dendritic pattern. The Maniar basin is in Elongated shape which indicates heavier flow for the long duration. The runoff estimation by SCS-CN curve method is determined by integrating land Use/land cover classification with antecedent moisture condition and hydrological soil groups. The study area receives the good rainfall but most of it is lost by surface runoff due to overland flow and Clay soil texture present in the study area. It was perceived from the results that overall increase in runoff is directly proportional to precipitation in the study area. The daily precipitation data from 11 weather stations which are present in the study area have been collected during the years 2010 - 2018 and were used to estimate the daily runoff from the basin. Daily and annual runoff has been calculated from the monthly rainfall data for the years of 2010 to 2018 in the basin.

Water Harvesting For Sustainable Development of El-Hraka Basin in the North-western Coast of Egypt

Water resources in the northwest coast of Egypt are very limited in terms of quantity, as they are produced mainly from rainwater in the winter season. Water scarcity is the main impediment to development activities in the region. Prepare Water Harvesting (RWH) is one of the most effective solutions to beat this problem. El-Hraka basin is located in northwest coast of Egypt near Matrouh city between Latitude s31° 13' 23.926 N , 30° 55' 54.439 N and longitudes 27° 25' 45.747 E and 27° 20' 5.097 E. The aim of this study is to assess the potentiality of El Harak basin for water resources management and agricultural development activities. The study aimed also to predict annual peak flow and runoff water volume, as well as the 20, 10, 5, 3, and 2year return periods. Results referred that El-Hraka basin characterized by area of 178.31km2, basin length of 33.70 km, perimeter of 132.8 km, and gentle slope of 0.012 m/m. There are four types of land use/land cover in the study basin: agriculture land, bare land, rocky areas and urban representing 3.45, 92.98, 3.41 and 0.16% of El Hraka basin, respectively. There are two hydrologic soil group of the study basin A and C depending on the soil texture. The Curve Number (CN) of the study basin depending on the land use / land cover and the hydrologic soil groups. Its average values are 73.67 for El-Hraka basin. The annual runoff water volumes are 10583.29 m3. However, the annual infiltration volumes are 8195.01m3. The peak flow of the 20 year return period flash flood is 29.24m3/s for the study basin, while the value for the 10 year return period flash flood is 17.98 m3/s. The peak flow for the 5 year return period reaches 9.50 m3/s for the 3 year return period peak flow is 3.78 m3/s, while the 2 year return period peak flow is 0.75 m3/s. The runoff volume of the 20 year return-period is 2777883.3 m3, while for the 10 year return period is 1713298.9 m3. The Runoff volume for the 5 year return-period reaches 906578.6m3; and for the 3 year return period runoff volume is 359883m3, while the 2 year return period is 69989.4 m3 for the study basin.

Land-Use and Land-Cover Change in Dhaka Eastern Region and Its Impact on Surface Run-off

The aim of this study is to identify the impending urbanization-led land-use and land-cover (LULC) change of Dhaka Eastern Region (DER) and assessing its impact on surface runoff. Remotely sensed image data and proposed land-use plans for DER is analyzed and mapped in this study to detect the changes of LULC. A faster pace of land transformation was observed during 2016-17 from unpaved to the paved surface. Four post-developed LULC scenarios were predicted from the classified Landsat imagery of 2016-17 with increasing imperviousness. Runoff was estimated by SCS-CN method integrating RS and GIS tools. LULC changes according to land cover classes were assimilated with the hydrologic soil groups and then runoff depths were estimated for annual rainfall events in DER. Like the slower trend of urbanization, area-weighted CN also increased slowly during 2016-17 but followed a moderate leap in RDP and scenario-1. However, CN dropped in scenario-2 mainly due to the change in land-cover by infilling of highly permeable hydrologic soils. Predicted scenario-3 and 4 resulted in higher CN respectively because of increasing imperviousness in LULC. Higher CN resulted in higher runoff and more drainage requirements. RDP scenario or the predicted scenario-1 with CN 84 is potentially a viable LULC option for DER by 2035 and beyond that may cause more than 30% to 50% runoff comparing to the representative 2010 LULC condition.

Susceptibility Mapping of Soil Water Erosion Using Machine Learning Models

Soil erosion is a serious threat to sustainable agriculture, food production, and environmental security. The advancement of accurate models for soil erosion susceptibility and hazard assessment is of utmost importance for enhancing mitigation policies and laws. This paper proposes novel machine learning (ML) models for the susceptibility mapping of the water erosion of soil. The weighted subspace random forest (WSRF), Gaussian process with a radial basis function kernel (Gaussprradial), and naive Bayes (NB) ML methods were used in the prediction of the soil erosion susceptibility. Data included 227 samples of erosion and non-erosion locations through field surveys to advance models of the spatial distribution using predictive factors. In this study, 19 effective factors of soil erosion were considered. The critical factors were selected using simulated annealing feature selection (SAFS). The critical factors included aspect, curvature, slope length, flow accumulation, rainfall erosivity factor, distance from the stream, drainage density, fault density, normalized difference vegetation index (NDVI), hydrologic soil group, soil texture, and lithology. The dataset cells of samples (70% for training and 30% for testing) were randomly prepared to assess the robustness of the different models. The functional relevance between soil erosion and effective factors was computed using the ML models. The ML models were evaluated using different metrics, including accuracy, the kappa coefficient, and the probability of detection (POD). The accuracies of the WSRF, Gaussprradial, and NB methods were 0.91, 0.88, and 0.85, respectively, for the testing data; 0.82, 0.76, and 0.71, respectively, for the kappa coefficient; and 0.94, 0.94, and 0.94, respectively, for POD. However, the ML models, especially the WSRF, had an acceptable performance regarding producing soil erosion susceptibility maps. Maps produced with the most robust models can be a useful tool for sustainable management, watershed conservation, and the reduction of soil and water loss.

Estimation of Surface Water Runoff for a Semi-Arid Area Using RS and GIS-Based SCS-CN Method

The proper planning of storage structures, waterways, irrigation schemes, water harvesting, erosion control structures, and groundwater development strategies requires accurate estimation of surface runoff. However, hydrologists in Saudi Arabia face serious challenges, specifically due to the rare availability of surface runoff data. In this study, the soil conservation service-curve number (SCS-CN) method integrated with geographic information system (GIS) and remote sensing (RS) was utilized to estimate the surface runoff in Wadi-Uranah basin, in the western region of Saudi Arabia. Different thematic maps such as slope, hydrologic soil group (HSG), land use/land cover (LULC), and daily rainfall have been created in GIS environment and processed to generate the curve number (CN) and surface runoff maps. Based on the soil classification results, the study area was categorized into two HSGs (B and C). The dominant HSG was group C, representing about 98.8% of the total area. The LULC analysis showed four main land use types in the study region: urban, rocks, barren soil, and agricultural areas. Furthermore, the finding results showed that CN values for the normal conditions (CNII) ranged between 74 and 93 in agricultural and both urban and rock areas, respectively. The CNII values were further corrected using slope data to derive slope-adjusted CNII. Moreover, the rainfall-runoff results showed an increase in the daily runoff of the study region with a minimum of 15 mm to a maximum of 74 mm. Another interesting result was rainfall-runoff linear regression analysis that showed a good correlation of 0.98. Additionally, the peak runoff hydrograph flows for 10-, 50-, and 100-year return periods obtained from the SCS-based dimensionless unit hydrograph were 828, 1353, and 1603 m3/s, respectively. Therefore, this study highlights that the SCS-CN method integrated with RS and GIS deserves further attention for estimating runoff of ungauged basins for better basins management and conservation purposes.

Surface runoff estimation of Wadi Ba Al-Arid watershed North East Libya, using SCS-CN ,GIS and RS data

The aim of this study is to estimate runoff in Wadi Ba Al Arid watershed for a period of ten years 2009-2018 by Soil Conservation Service Curve Number (SCS-CN) method in combination with the GIS techniques using remote sensing data. The used data are the daily rainfall data from NASA Prediction of Worldwide Energy Resource (POWER), digital elevation data (DEM) from ALOS PALSAR RTC , satellite imagery from the European Space Agency (ESA) Sentinel, and soil data represented in soil maps of a scale 1: 50,000 and some local studies carried out by several Libyan institutions. The overall area of the watershed is about 136.4 km2 and perimeter107.3 Km. The watershed upstream and downstream is well recognized due to the topographical difference as a result of the tectonic geology. Soil maps were processed and classified into hydrologic soil groups (HSG), where the dominant HSG in the study area are C and D. The Landcover/Land use (LULC) was classified into five classes (forest, shrubs, agriculture, barren land) and built up. The HSG and LULC layers were intersected and the CN values and the weighted curve number for each Antecedent Moisture (AMC) condition were assigned. Furthermore, the runoff depth was estimated and the average runoff volume for ten years during 2009–2018 in the study area was estimated by 1.67 Mm3 which represents 4.6 % of the observed average annual rainfall as 264.3 mm during 2009-2018. The rainfall-runoff relationship has shown a strong correlation with the value of 0.75.

Rainfall-surface runoff estimation for the Lower Bhavani basin in south India using SCS-CN model and geospatial techniques

Rainfall and surface runoff are the two most important components, which control the groundwater recharge of the basin. The long-term groundwater recharge of an aquifer gets affected by the population growth, irregular agriculture activities and industrialization. Hence, estimation of rainfall-surface runoff is very much essential for proper groundwater management practices. In the present study, Soil Conservation Service Curve Number (SCS-CN) model was employed in combination with geospatial techniques to estimate rainfall-surface runoff for the Lower Bhavani River basin in South India. To develop the SCS-CN model, rainfall data were obtained for 33 years (1983–2015) from 22 rain gauge stations spread over the basin. IRS LISS-IV satellite data of 5.8 m spatial resolution were used to analyze the land use/land cover (LU/LC) behavior. Based on the soil properties, four Hydrological Soil Groups (HSG) were identified in the basin which is most significant for surface runoff estimation. Curve Number (CN) values were obtained for various Antecedent Moisture Conditions (AMC) such as dry condition (AMC I), average condition (AMC II) and wet condition (AMC III). Spatial distribution of CN values was plotted using Geographical Information System (GIS) for the entire Lower Bhavani Basin to assess the surface runoff potential. The results indicate that the annual rainfall varies from 267 mm (2002) to 1528.6 mm (2005), and the annual surface runoff varies from 102.04 mm (1985) to 463.02 mm (2010). The SCS-CN model outputs predict that the average surface runoff of the basin is 211.99 mm, and the average surface runoff volume is 81,995,380 m3. The study also indicates that nearly 53% of the basin area is dominated by high to very high surface runoff potential. Finally, the output of surface runoff potential was validated with the Average Groundwater Level Fluctuation (AGLF) observed in 57 wells spread over the entire basin. The basin AGLF ranges from 2.32 to 21.72 m. The surface runoff potential categories are satisfactorily matching with the AGLF categories. Moderate surface runoff as well as moderate AGLF zones mostly occupy the central portion of the basin, which possess good groundwater potential. However, the high surface runoff zones in the basin lead more surface water flow into the river channels, which reduce the infiltration rate and decline the water table. This problem can be solved by constructing suitable artificial groundwater recharge structures across the river channels in the high surface runoff potential areas.

Parameters influencing run-off on vegetated urban soils: A case study in Marseilles, France

In urban areas, episodes of extreme precipitation may generate run-off floods, but urban soils are seldom considered in spatial planning documents. Our aim was to assess the infiltration of vegetated urban soils and to identify the soil parameters affecting infiltration in order to explore the potential of these soils for run-off mitigation under a Mediterranean climate with extreme precipitation episodes. We compared vegetated soils in the “urban” zone of the Marseilles’ 16th district (France) either lying on former clay quarries or tile factories (T) or not (NT) and with different land-uses. We used a simplified method to measure field saturated hydraulic conductivity (Kfs), measured penetration resistance in the first 0.15 m (Qd) and analysed physico-chemical properties in the first horizon. Levels of run-off production were estimated according to Kfs and an adaptation of USDA Hydrologic Soil Groups. All soils were Technosols or Anthrosols regardless of their prior history. We found that land-use history influenced Kfs, with T soils and soils with current vegetated land-use younger than 13 years having lower Kfs than NT soils and soils with land-use older than 13 years. Soil organic matter content influenced Kfs positively when soils were young, while vegetation cover and penetration resistance (most of the soils had Qd > 2 MPa) had not a clear effect on Kfs. Overall, combining Kfs and soil depth, 14.3% of the T soils and 84.6% of the NT soils had low levels of run-off production. It is therefore recommended that 1) Technosols or Anthrosols should be characterised for their unique physico-chemical and physical properties but also for their land-use history, and 2) the infiltration of these soils should be considered in spatial planning documents.

Quantification of Sub-Watershed Wise Surface Runoff Using Remote Sensing, GIS and Soil Conservation Services – Curve Number Method, Karur District, Tamil Nadu, India

Runoff is one of the significant hydrologic variables used in generally of the water resources applications. The Soil Conservation Service–Curve Number (SCS–CN) method is adopted for the evaluation of surface runoff in the Karur District, Tamil Nadu, India using multispectral remote sensing data, rainfall data and curve number approach. The weighted curve number is determined based on antecedent moisture condition (AMC)-II with an integration of Hydrologic Soil Groups(HSGs) and land use/ land cover categories. The daily runoff was estimated for rainfall Period September 2018 to November 2018. The results of the present study shows that the runoff depth for the study area are ranging in between 106.57 and 713.65 mm and runoff volume are ranging in between 2.75 and 126.21 mcm. In the present study, the methodology for determination of runoff for study area using remote sensing, GIS and SCS–CN method was described. Keywords: Surface runoff estimation, sub-watershed, Remote Sensing, GIS, Curve number.

Flood susceptibility mapping in densely populated urban areas using MCDM and fuzzy techniques

Flood, as the most destructive natural phenomenon in Iran, causes a multitude of deaths and financial losses every year in different parts of the country. This study sought to determine flood-prone areas in one of the Ajay River sub-basins (Lighvan River basin), Iran using Analysis Hierarchy Procedure (AHP) for ranking, fuzzy logic (FZ) for integrating with AHP in order to rank and Weighted Linear Combination (WLC) for the combination of maps. For this purpose, the geomorphologic and hydrologic factors affecting the occurrence of floods such as slope, distance from the river, Hydrological Soil Group (HSG), Curve Number (CN), runoff, lithology, land use, drainage density, Gravilius coefficient in each of the 23 sub-basins were considered based on the literature. The desired criteria and sub-criteria were weighted by the AHP and FZ, respectively. Then, WLC aggregation method was applied to generate the flood susceptibility map in five classes. The results earned by the combination of Multi-Criteria Decision Analysis (AHP and WLC)-FZ (MCDM-FZ) show that 28% of the area is in high and very high hazard classes that these areas are located almost at the entrance of Tabriz city, which is a densely populated urban area. Basic measured need to be taken in the upstream of the basin especially in areas with the high flood zone.

Morphologic and Engineering Characteristics of Watersheds (A Case Study: East Wasit Watersheds that Feed the Al-Shewicha Trough - Iraq)

The Al-Shewicha Trough represents a real flood hazard to Kut City (capital of Wasit Province, Iraq) as well as to the other cities along the Tigris River downstream Kut Barrage, especially heavy monsoon years. Under the acute lack of water resources around the world, many modern techniques in unconventional innovative water resources management were developed. In this study, ArcGIS was used in the morphologic analysis of six river basins which represent the main sources of feed for the Al-Shewicha Trough. The results show that the high value of the greatest length of a basin 1,5 and 6 indicate that these watersheds have high value of concentration time (tc) which delays the peak flow. All basins consisted of very coarse and permeable subsurface strata, and were of coarse texture. Circularity ratio Form factor and elongation ratio shows an elongated shape of all basins with lower peak flow and long duration. Analyses of soil data demonstrate that the soil type that covers a large area is loam soil within the hydrologic soil group type B, which indicates that all basins have low permeability and high runoff. The most predominant land use was bare soil and all basins have a covering of poor vegetation which highlights the basins that are most susceptible to erosion, thus resulting in the generation of higher sedimentation.

Land-use changes in the periurban interface: Hydrologic consequences on a flatland-watershed scale

The aim of this work was to analyze the hydrologic effects on surface runoff and infiltration of changes in land use and land coverage. The periurban-flatland watershed of El Pescado Creek (Argentina) was the study site investigated. We used Geographic-Information-System techniques together with the curve-number method (CN) to estimate the surface runoff in five land-use scenarios having increasing levels of anthropic impact (years 1986, 1996, 2006, 2016, and 2026) considering two rainfalls and the antecedent-runoff conditions (ARC) defined by that methodology. We identified three hydrologic-soil Groups (B, C, and D) and five land uses (grassland, forest, urbanization, greenhouses, and poultry farms). Land use and land coverage change process increased CN values, and consequently the estimated surface runoff, especially in the upper watershed. Changes towards impervious (687 ha with greenhouses and poultry farms) or semi-impervious land coverage (800 ha with urbanizations) affected infiltration. The most contrasting results were related to the ARC I, II, and III weighted-average infiltration of the watershed that diminished from above 93.0%, down to 88.5% and finally to 50.4%, respectively (calculated with data from the 55.8-mm rainfall), and from 86.6%, to 58.3%, and to finally 28.8% (calculated with data from the 117.8 mm rainfall). Simulating a near-future land-use scenario (year 2026) enabled us to estimate the watershed pattern by adding new area containing semi-impervious and impervious land coverage. The estimated weighted-average infiltrations (ARC II) were 81.3% and 54.9%, for the above 55.8-mm and 117.8-mm rainfalls, respectively. Changes concerning infiltration might be disturbing the natural recharging process of aquifers, carrying out modifications in the hydrodynamics of the watershed, and also affecting water supply for human activities in the territory.

Linking Global Land Use/Land Cover to Hydrologic Soil Groups From 850 to 2015

AbstractThe characteristics of soils in part determine human‐induced land use and land cover (LULC) change, and together, soil properties and LULC directly impact global water, energy, and biogeochemical cycles. Plant health and the exchange of energy, water, and biogeochemical components at the surface interface are partly controlled by soil properties. Different soil types modify vegetation responses to existing climate forcings, and each soil type also responds differently to the same land‐use practice. Currently, Earth system models often use single soil columns with averaged properties. This leads to uncertainties in assessing LULC impacts. To improve the estimates of land surface change in Earth System Models, we link an existing LULC data set to four hydrologic soil groups from 850 to 2015, based on demonstrated soil preferences for eight LULCs under current conditions. We conclude that humans prefer hydrologic soil groups in order from B, D, C, to A. This ranking was applied to construct the history of LULC on each soil type at the 0.5° grid resolution. Results primarily distribute croplands to hydrologic soil group B in 850, while hydrologic soil group A has the most undisturbed area. Over time, good soils (hydrologic soil groups B and D) experience increased use for cropland areas, while poor soils (hydrologic soil groups C and A) are occupied predominantly by increasing areas in grazing land and secondary nonforests. The results provide better land surface characteristics to improve Earth systems modeling.

Determination of Hydrologic Soil Group from Soil Map Unit of Indonesia in Pataruman Water Catchment Area

Hydrologic Soil Group (HSG) for each region is different depending on soil conditions. It is one of the key elements in the NRCS-CN determination to account for the rain-runoff relationship. But unfortunately in Indonesia there is no map of HSG. Adidarma (2013) has conducted the research about HSG determination by using hydrogeology map. However, the map has a long process of pedotransfer and HSG parameter approach is still generally and qualitative. Furthermore, Ramadan (2017) has done research of HSG determination with HWSD map; the map is a global map which depth of information type of soil is less profound. Related to those problems, the researcher will conduct the determination of HSG in accordance with the condition of land in Indonesia by using Land Map Unit (SPT) Indonesia. HSG will be overlay with the transparent of land in Pataruman Water Catchment Area (WCA) until obtained the value of NRCS-CN and then the discharge plan will be calculated and will be calibrated with debit recording in Bendung Pataruman.

Unit hydrograph method for curve number validation in hydrological modeling: case study of Welaran Watershed, Karangsambung, Kebumen

Unit hydrographs, which have long been used in hydrological analyses, assume or require evenly distributed rainfall as their input. In practice, such a requirement is met when the methods are applied to small watersheds. This study aim to validate the curve number in hydrological modelling used unit hydrograph. The Welaran Watershed in Karangsambung has an area of 11.6 km2. More than 50% of it is covered by rice fields, while the rest is by dry agricultural lands, multiple-species plantations, and settlements. This watershed has been installed with a stream gauge equipped with AWLR and ARR. Based on the automatically recorded flood and rainfall data, a hydrological analysis was performed to generate unit hydrographs. Baseflow (losses), separated from the hydrograph, was compared with a loss of water using the Curve Number (CN) method. CN was derived from a reference table containing land use (LU), soil hydrological group, andantecedent moisture condition (AMC).The CN of the study area was 67, which is the weighted value of the mapping unit. Insome rainfall-runoff events, the unit hydrograph approach yielded curve numbers varying between 23-82 for eight selected rainfall events. It indicates that many factors shape the diversification of rainfall-runoff interaction in a watershed, including the actual distribution of rain. Also, AMC seemed to be distributed according to not only the amount of previous rain but also other factors that need further study.

Financial effect of limiting pesticide use near schools for almonds in nine counties depends on soils and weather

Effective Jan. 1, 2018, the California Department of Pesticide Regulation enacted a regulation regarding the use of pesticides near public K-12 schools and licensed child day care centers, including a provision that bans specific types of applications, including air-blast and air-assist, during weekday school hours (6 a.m. to 6 p.m.) to provide an additional safety margin for pesticide exposure beyond those provided by other regulations. We considered the financial effect on almond growers in nine counties, accounting for four-fifths of total almond production in 2014, if they had been unable to complete a standard spring disease management program on any buffer zone acreage. Results indicated that total annual losses for those counties if such a regulation had been in effect would have been $8.7 million, with per-acre losses ranging from 22% to over 50% of total operating costs, depending on the county. However, using a methodology that took into account historical weather and soil hydrologic group data, we estimated average annual losses in the nine counties among almond growers would have been under $0.2 million because the regulation would have affected the number of sprays completed for relatively few acres in relatively few years.

Analysis of classification hydrologic soil group distribution based on infiltration rate of horton method in the upper Ciliwung watershed

Runoff coefficient or Curve Number (CN) is a parameter value needed to describe runoff in accordance with the intended land use. In determining CN values, it is necessary to take account the Hydrologic Soil Group. The Hydrologic Soil Group (HSG) consists of 4 groups, which are: A, B, C, and D. In order to classify the appropriate HSG, several methods can be used, namely: soil properties, soil maps, or minimum infiltration rates. In this research, an HSG classification distribution analysis will be carried out based on the infiltration rate obtained from actual conditions found during observation in the research site. This research was conducted in 13 locations, situated in the Upper Ciliwung watershed. The division of 13 locations is based on the distribution map of the HSG according to the Geological Information Agency and also the map of the distribution of Upper Ciliwung sub-bases. In its classification, each HSG has a different infiltration rate value. In this study, an analysis of the distribution of HSG classification based on the infiltration rate was obtained from direct observation on the research site. The study was conducted using a double-ring infiltrometer. The data obtained from the study were then processed using parameter estimation and the Horton Method to obtain the Horton infiltration rate. When the infiltration rate value is known, the corresponding HSG can then be determined for the soil at that particular location. With Inverse Distance Weighted in ArcMap, a map of the spread of infiltration rate and classification of HSG will be obtained in the Upper Ciliwung watershed. The infiltration rate obtained in the Upper Ciliwung watershed ranges from 0.15-12.6 cm/hour. The distribution of HSG is also found in the Upper Ciliwung watershed, consisting of groups A, B, and C.

Characteristics of Flood Water Level Based on Hydrologic Soil Group Analysis in Temef Watershed

Temef Watershed is located in the Benanain River Basin with a catchment area of 551.50 km2. River characteristics in the Temef Watershed are influenced by three main river streams from upstream to downstream. Conventional collection of data on watershed characteristics requires a relatively long process and time. However, when based on Geographic Information Systems (GIS), the cost and time will be more efficient. The floodwater level is affected by the amount of rainwater runoff that occurs in the Temef Watershed. The amount of runoff depends on the level of soil permeability and land cover. To determine the level of soil permeability, hydrogeological maps are used. Based on this, a study of the characteristics of flood waters from GIS-based hydrogeology is needed. The analysis method used ArcGIS overlay on hydrogeological maps, while data on watershed characteristics used the Archydro and HEC-GeoHMS features. The results of the analysis showed a level 3 permeability type with limestone lithology, solid volcanic breccia, sandy marlene, conglomerate, and alluvium consisting of sand and gravel having moderate to high permeability. The metamorphic and basalt rocks have low to moderate permeability and the scaly clay has low to very low permeability. This condition causes runoff that turn into flood streams.