Water In Ditches Research Articles

Effects of Climate Change on Poultry Production in Ebonyi State, Nigeria

Three agricultural zones of Ebonyi State, Nigeria, were considered for this study. Using Pearson Product Moment Correlation (PPMC) to establish the relationship between the variables and how one independent variable influences the dependent variables. The study aimed at examining the effects of climate change on poultry production. The study's primary objectives were to assess the socioeconomic characteristics of poultry farmers, ascertain the extent of climate awareness, determine the effect of climate change on poultry production, determine climate change adaptation strategies for coping with it, and identify the constraints encountered in poultry production. Four local government areas in the state of Ebonyi were the locations of data collection from September to October 2021. A multistage sampling procedure was used for the collection of respondents. The study found that 56.9% of the respondents were female, 42.2% were in their active age 30 to 40, 54.9% had a Bachelor’s degree, 64.7% had spent more than years of farming experience, and 29.4% were managers of their poultry production. Farm size had little effect on poultry production; climate change had an effect on feed consumption and has caused the spread of pests and diseases and the death of young ones. According to the study's findings, the respondents were in agreement that changing to intensive livestock management and collecting runoff water in ditches during periods of drought constituted adaptation to climate change. It was determined that climate change had an enormous and negative effect on poultry production through insect infestation and disease outbreak. Therefore, relevant Nigerian government agencies should offer financial assistance to poultry farmers along with adaptation training.

The impact of beaver dam removal on the chemical properties of water in drainage ditches in peatland forests

ABSTRACT Despite near-extinction in the nineteenth century, after efficient restoration measures the population of Eurasian beaver (Castor fiber L.) in Latvia currently is viable and growing. While the ecological effect of the species on water quality and biodiversity is generally positive, the high number of animals in production forests often creates challenges for management. Drainage ditches are among the most favoured habitats of beavers resulting in flooded stands, reduced tree growth and economical losses. The aim of the study was to evaluate the chemical properties of water in forest drainage ditches, affected by beaver activity, and their changes after the dam removal. Chemical composition of surface water in ditches was analysed in sampling points above dam, below dam and in the ditch itself after removal of the dam; results compared to pristine beaver site nearby on a small stream. Results did not show significant differences between concentrations above and below dams. After removal of the dams, significant increase in DOC, N-NO3 -, N-NH4 + and TSS concentrations and significant decrease in TP concentrations were observed in some of the sites. Observed concentrations of all measured parameters were significantly lower in pristine beaver site than in beaver sites on drainage ditches.

Characterization of Nutrient and Metal Leaching in Roadside Ditches Maintained with Cool and Warm Season Grasses

Roadside ditches play an important role in the quantity and quality of receiving waters. Very little, however, is known about the fate and transport of nutrients and trace metals in roadside ditches, especially their leaching to shallow groundwater. This study sought to document selected water quality constituent levels in infiltrated water (i.e., leachate) in roadside ditches maintained with permanent vegetation. Leachate sampling wells were installed in four roadside ditches, and water samples were collected from the wells following major rainfall events during the years 2016 and 2017. The samples were analyzed for nutrient and metal concentrations. Results indicated that nutrient concentrations in the water samples range from 0.00600 to 0.0107 mg/L for orthophosphate (PO4–P), 0.00500 to 6.80 mg/L for nitrate (NO3–N), 0 to 0.007 mg/L for nitrite (NO2–N), and 0.0100 to 314 mg/L for chloride (Cl−). Concentrations of the metals examined varied between 0.0100 and 104 mg/L in water samples. While there was no specific pattern in both nutrient and metal concentrations when roadside ditches maintained with cool season grass were compared to those of warm season grass ditches, results suggest that grass types will likely affect differently uptake of nutrients and metals in the ditches.

Leaching of heavy metals and barium from forest roads reinforced with fly ash

The aim of this study was to determine the effect of leaching of heavy metals (Cr, As, Cd, Cu, Ni, Pb, Zn, Co, Mo) and earth-alkaline metal, barium (Ba), on the percolation and ditch water quality from the forest roads that contained ash in the road structures. Water quality was studied in the immediate vicinity below the ash layers as well as deeper in the road structure. Water quality was also determined in the drainage water in ditches that crossed the forest roads. A mixture of wood and peat based fly ash was used in the road structures. The treatments were: 1) no ash, 2) a 15 cm layer of ash/gravel mixture, 3) a 20 cm layer of ash/gravel mixture, 4) a 25 cm layer of ash, and 5) a 50 cm layer of ash. Large variation in the concentrations of Cr, As, Cu, Ni, Pb, Mo and Ba in the percolation water, even within the same treatment, caused difficulties to generalize the results. The concentrations of Cr, As, Ni, Pb, Mo and Ba in water samples were high in some treatment plot lysimeters containing ash compared to the control (no ash). On the other hand, many lysimeters had low and similar concentrations in water samples in the treatment plots containing ash compared to concentrations in the control plots. The ash in the roads did not affect the concentrations in the ditches. The leaching is uneven and seems to take place only from some parts of the ash layer. Risk for leaching is minimal if such parts are not widely spread.

Contrasting soil property patterns between ditch bed and neighbouring field profiles evidence the need of specific approaches when assessing water and pesticide fate in farmed landscapes

Farm ditch networks, infrastructures designed to regulate excess water in cropped landscapes, constitute pesticide dispersal pathways or buffer zones, depending on their soil properties. Despite the key role that ditch soils play in the regulation of water and pesticide fate, their properties, especially in intermittently flooded ditches, remain poorly characterized. Therefore, our aim was to evaluate the specificity of ditch material properties to determine whether ditches require an approach that differs from that of field soils when studying water and pesticide fate in farmed landscapes. We thus analysed the variations in the pedological, herbicide sorption and flow properties of soil materials along a 2D cross-section of an intermittently flooded ditch in the Roujan catchment of southern France. We found that the upper part of the ditch bed soil profile is composed of 3 horizons that formed after the original creation of the ditch, most likely via the deposition of field-eroded particles and the accumulation of organic matter. These specific horizons have greater porosity, mostly due to their dense root systems, and contain up to 2 times more organic carbon than the neighbouring banks or field soils. Consequently, the hydraulic conductivity is greater, and the sorption of hydrophobic herbicides is up to 2 times greater in ditch bed materials than it is in soils located farther away from the ditch surface. Moreover, significant macroporal flow was evidenced in both profiles but with different contribution to the global flow. The contrasts in the hydrodynamic and sorption properties between both the ditch bed and banks materials likely results in significantly different water and pesticide infiltration patterns in ditches compared to crop fields. Given these differences, we recommend investigating the specific properties of ditch beds when studying and modelling water and pesticide fate in croplands.

Characterisation of agricultural drainage ditch sediments along the phosphorus transfer continuum in two contrasting headwater catchments

This study investigated the phosphorus (P) source, mobilisation and transport potential of ditch bed sediments as well as surrounding field and bank soils in two agricultural headwater catchments with contrasting soil drainage capacities. This information is important for discerning the potential for ditches to attenuate or augment transfers of P from upstream sources and thus for developing appropriate management strategies for these features. Phosphorus sources were characterised using the Mehlich3-P, water-soluble P and total P tests. Phosphorus mobilisation potential was characterised using the Mehlich3-AL/P, Mehlich3-Ca/P and DESPRAL P tests. Phosphorus transport potential was characterised using data collected on the presence/absence of surface water in ditches during field surveys and downstream turbidity data. Ditch sediments had similar P source contents (Mehlich3-P, water-soluble P and total P) to the surrounding field soils and higher P contents than bank soils. However, calcium contents of sediments in the poorly drained catchment reflected the deep sub-soils rather than the surrounding field and bank soils. Mehlich3-Al/P and Mehlich3-Ca/P contents of ditch sediments in the well (non-calcareous) and poorly (calcareous) drained catchments respectively indicated potential for P retention (above thresholds of 11.7 and 74, respectively). However, sediments were less aggregated than field soils and may mobilise more particulate P (PP) during rain events. Nevertheless, the majority of surveyed ditches dried out from March to September 2011; thus, their potential to mobilise PP may be less important than their capacity to attenuate soluble and PP during this time. In these and similar catchments, soluble P attenuation and particulate P mobilisation should be maximised and minimised, respectively, for example, by cleaning out the sediments before they become saturated with P and encouraging vegetation growth on ditch beds. This study also highlighted the influence of deep sub-soils on soluble P retention in ditches and thus the utility of characterising soils below depths normally included in soil classifications.

Enhancing the Biodiversity of Ditches in Intensively Managed UK Farmland.

Drainage ditches, either seasonally flooded or permanent, are commonly found on intensively managed lowland farmland in the UK. They are potentially important for wetland biodiversity but, despite their ubiquity, information on their biodiversity and management in the wider countryside is scarce. We surveyed 175 ditches for their physical and chemical characteristics, spatial connectivity, plant communities and aquatic invertebrates in an area of intensively managed farmland in Oxfordshire, UK and collected information on ditch management from farmer interviews. Water depth and shade had a small impact on the diversity of plant and invertebrate communities in ditches. Increased shade over the ditch channel resulted in reduced taxonomic richness of both channel vegetation and aquatic invertebrates and channel vegetation cover was lower at shaded sites. Invertebrate taxonomic richness was higher when water was deeper. Spatial connectivity had no detectable impact on the aquatic invertebrate or plant communities found in ditches. The number of families within the orders Ephemeroptera, Plecoptera and Trichoptera (EPT), which contain many pollution-sensitive species, declined with decreasing pH of ditch water. As time since dredging increased, the number of EPT families increased in permanent ditches but decreased in temporary ditches. Whether or not a ditch was in an agri-environment scheme had little impact on the reported management regime or biodiversity value of the ditch. Measures for increasing the amount of water in ditches, by increasing the water depth or promoting retention of water in ditches, could increase the biodiversity value of ditches in agricultural land. Some temporary ditches for specialised species should be retained. Reducing the amount of shade over narrow ditches by managing adjacent hedgerows is also likely to increase the species diversity of plant and invertebrate communities within the ditch. We recommend that to preserve or enhance the biodiversity value of ditches, and improve their ecosystem service delivery, management prescriptions for hedgerows adjacent to ditches should differ from those aimed at hedgerows only.

Fate of Extended-Spectrum β-Lactamase-Producing Escherichia coli from Faecal Sources in Surface Water and Probability of Human Exposure through Swimming.

The goal of this study was to determine the fate of ESBL-producing Escherichia coli (ESBL-EC) emitted from faecal sources in surface water, and the probability of human exposure through swimming. Concentrations of ESBL-EC were measured in recreational waters and in source waters, being water in ditches surrounding poultry farms and municipal wastewater. Additionally, the potential of ESBL-EC in source waters to reach recreational waters located downstream of these sources was modeled. Modeled ESBL-EC concentrations in recreational waters appeared to be mostly determined by the concentrations in the source waters and by subsequent dilution in surface water, and less by inactivation. The mean (95%) risk of human exposure to ESBL-EC per person per swimming event, as assessed from measured ESBL-EC concentrations in recreational waters, was 0.16 (0.89) for men, 0.13 (0.72) for women and 0.20 (0.95) for children. Similar exposure risks were estimated for hypothetical recreational waters containing 100- or 1000-times diluted source water, located 10 days water travel time downstream of the sources. Human exposure to ESBL-EC through swimming is likely, if recreational waters are located downstream of poultry farms and municipal wastewater discharge points.

Evaluating flood risk and alterations to hydraulic patterns following installation of low-grade weirs in agricultural systems

Because low-grade weirs are designed to impede flow of water there is concern from producers that they will lead to decreased drainage and increased flooding in adjacent fields. The purpose of this study was to determine if weirs increased the risk of flooding and backflow. Analyses were conducted to evaluate the effect of low-grade weirs on hydrology. The first analysis targeted how weir-related modifications affected a single ditch by using pre and post weir-implementation data. Results of Wilcoxon–Mann–Whitney tests were mixed, with no significant differences for ditch W1 and significant differences at ditch W2 for both time to peak (p=0.009) and time to base (p<0.001) following weir installation. Differences in peak height were significant at W1 (p=0.004) and not significant at W2 (p=0.875). The second analysis determined if significant differences existed between ditches modified with weirs in general and ditches which were unmodified in general. Results of a MANOVA indicate no significant difference for time to peak (p=0.985) between ditches with weirs and those without weirs, and a significant increase in time to base in sites with weirs (p=0.003). The estimate of weir effect for time to base indicates that it takes approximately 23h 13min (s.e.=7h 30min) longer to return to initial water level when weirs are present. The third analysis considered differences between peak heights for ditches modified with weirs in general and ditches which were unmodified in general. Results of a Wilcoxon–Mann–Whitney test of normalized peak heights indicated that maximum peak heights during storm events were approximately 10% lower in ditches with weirs (18.4 vs. 28.5%, p=0.015). Results suggest weirs do not increase flooding potential but merely hold water in ditches longer by slowing return to pre-storm-event levels.

Estimating degradation rates in outdoor stagnant water by inverse modelling with TOXSWA: a case study with prosulfocarb

The regulatory risk assessment of pesticides requires the assessment of exposure of aquatic ecosystems in small surface waters adjacent to agricultural fields. This exposure is predicted using simulation models, for which an important input parameter is the degradation rate in water. In regulatory dossiers, the decline rate in water from outdoor mesocosms is often available, but this rate encompasses more processes than degradation. Therefore, a procedure was designed for estimating the degradation rate in water that was suitable for mesocosm studies with limited datasets, e.g. datasets lacking site-specific sorption coefficients and relevant sediment properties. The procedure, based upon inverse modelling with TOXSWA, has been tested on a dataset for prosulfocarb in stagnant ditches. A degradation half-life in the ditch water of 2.9 days (20 °C) was found. This short half-life was to a significant extent accounted for by biodegradation rather than hydrolysis or photolysis. This half-life was considerably shorter than the half-life in the water layer of two laboratory water-sediment system experiments. The estimation procedure resulted in a unique half-life for the degradation rate in water. Such outdoor mesocosm studies seem to be better suited to assessing the degradation rate in water in ditches than the conventional water-sediment studies.

Individual Differences in Feeding Habits in a Newly Established Great EgretCasmerodius albusPopulation: Key Factors for Recolonisation

After having almost completely vanished from The Netherlands by the 19th century, from the 1970s onwards the Great Egret is increasing in numbers again, particularly in the newly created wetland of Oostvaardersplassen. During the first 25 years, the rate of re-colonisation has been extremely low, the resident population never exceeding five breeding pairs. From 2000 onwards, however, following the extension of the surface area of shallow marshland, the number of breeding birds increased to 45 pairs. This paper deals with the feeding ecology of the Great Egret during 1976–99, when numbers were at a low level. Individual differences in food choice and feeding habits were studied in order to gain insight into the key factors for establishing and maintaining a healthy population. Observations on foraging birds were carried out during 1987–92. The birds foraged mostly within the reserve. From March to July they preferred foraging in ditches, changing to Reed borders of shallow pools and dry grasslands from August onwards. In the ditches, Three-spined Stickleback Gasterosteus aculeatus, other small fishes and tadpoles were the main prey (91.4% of all prey items). In the shallow water bodies the egrets caught almost exclusively sticklebacks, and in grasslands Common Voles Microtus arvalis. One bird was observed feeding near fishing boats, taking Perch Perca fluviatilis and Roach Rutilus rutilus of 10–20 cm length. When feeding on sticklebacks, a Great Egret had to forage for 1.5 to 3 hours to fulfil its daily needs. When scavenging on larger fish around fishing boats only 15 minutes sufficed, but the energy expenditure was likely to be higher due to commuting flights and inter-specific competition with Grey Herons Ardea cinerea. However, for the majority of Great Egrets the shallow and transparent water in ditches and pools with a high abundance of young sticklebacks and some coverage with emergent vegetations proved to be the most profitable feeding habitat. The decisive factor underlying the spectacular increase in recent years has probably been the creation of clear and shallow freshwater pools and inundated grasslands in the formerly dry border zone of Oostvaardersplassen. These foraging grounds lie close to undisturbed breeding sites. This finding may prove useful for wetland restoration elsewhere in The Netherlands.

Drainage of Ponded Surface by an Array of Ditches

A comprehensive analytical solution for the quantity of seepage into an array of fully penetrating ditches from a ponded surface has been obtained using hodograph and Schwarz – Christoffel transformation. The solution includes equations for the quantity of seepage from the seepage face part as well as the water depth part of the ditch. The solution also comprises expressions for the velocity potential at the stagnation point and the variation in seepage velocity. The variation in seepage quantity is like the shape of a curved channel whose boundary maps along a circle onto the hodograph plane. This shape is average of a semiellipse and a parabola. The seepage contribution from the nonseepage face is maximum for half full condition and it is half of the total seepage in an empty ditch (full seepage face). Irrespective of the spacing between ditches the quantities of seepage from the seepage face part and the nonseepage part are equal for one third full ditch. The solution also deals with special cases like single ditch, unequal spacing between ditches, and unequal depth of water in adjacent ditches. The expressions the quantity of seepage have been simplified in explicit algebraic equations through minimization of errors. The simplified expressions, which are near exact, result in answers in single step computations. Also, an example and graphs have been included to demonstrate the sensitivity of the parameters.

Hydrochemical assessment of the Rochefort marsh: Role of surface and groundwater in the hydrological functioning of the wetland

The interaction between a wetland (the Rochefort agricultural marsh) and its underlying aquifers was studied using both geochemical and isotopic approaches. Water from the various components of the hydrosystem (water from ditches, shallow ‘Bri’ groundwater (silty clay deposits), deep ‘Bri’ groundwater and groundwater in the Kimmeridgian aquifer (confined and unconfined) was sampled and analysed for major and trace elements (Sr, Br), stable water isotopes ( 18O and 2H) and Sr isotopes. The salinity of groundwater in the marsh (Cl up to 15.5 g/l) can be attributed to seawater trapped in the clay sediments during the Flandrian (12,000–6400 BP). The groundwater has since undergone more or less major chemical evolution due to water–rock interactions and mixing with fresh water (rainwater, ditch water and Kimmeridgian groundwater from the edge of the marsh). The chemical characteristics of the groundwater in the confined Kimmeridgian underlying the Bri formation exclude the possibility of a salt wedge. The combined use of δ 18O, δ 2H, Cl, Br and Sr contents and 87Sr/ 86Sr ratios enabled exchanges between surface water in marsh canals and ditches and groundwater in the shallow Bri aquifer (<2 m), and between groundwater in the deep Bri (>7 m) and in the confined Kimmeridgian (>18 m) aquifers, to be defined and quantified. During the summer, the ditches recharge the shallow Bri aquifer by sub-irrigation (gravity flow) by up to 26%. The presence of a very compact layer of clay, 1–2-m deep, prevents the rapid recharge of the deep Bri aquifer by rainfall and direct hydraulic connections between the ditches and the deep Bri aquifer. On the scale of the marsh, the confined Kimmeridgian groundwater recharges the Bri aquifer by upward flow (maximum contribution estimated to be 76±13%), this flow being relatively limited and preferentially on the edge of the marsh. The deep Bri groundwater contributes very locally to recharging the confined Kimmeridgian aquifer (maximum contribution estimated to be 61±36%). This study demonstrates the interest in combining hydrological and geochemical tools in order to identify and quantify the hydraulic interconnections between a wetland and its groundwater components. A prior understanding of how wetlands function is crucial for the sustainable management of such ecosystems.

Stereotyped sequence of mating behavior in the Far Eastern catfish, Silurus asotus , from Lake Biwa

Mating behavior of the Far Eastern catfish, Silurusasotus (Siluriformes: Siluridae), was observed in a ricefield system facing the shore of Lake Biwa in mid-May to early June in 1990–1997. A set behavioral sequence similar to those of two other silurid fishes, S. biwaensis and S. lithophilus, both endemic to the Lake Biwa system, was observed: “chasing,”“clinging,”“enfolding” while “squeezing” by the male, and “circling” by the spawning pair. This form of mating behavior is quite different from that of S. asotus reported from the Ooi River system in Kyoto Prefecture, which mainly spawns in running water in ditches.

Artificial recharge of groundwater: hydrogeology and engineering

Artificial recharge of groundwater is achieved by putting surface water in basins, furrows, ditches, or other facilities where it infiltrates into the soil and moves downward to recharge aquifers. Artificial recharge is increasingly used for short- or long-term underground storage, where it has several advantages over surface storage, and in water reuse. Artificial recharge requires permeable surface soils. Where these are not available, trenches or shafts in the unsaturated zone can be used, or water can be directly injected into aquifers through wells. To design a system for artificial recharge of groundwater, infiltration rates of the soil must be determined and the unsaturated zone between land surface and the aquifer must be checked for adequate permeability and absence of polluted areas. The aquifer should be sufficiently transmissive to avoid excessive buildup of groundwater mounds. Knowledge of these conditions requires field investigations and, if no fatal flaws are detected, test basins to predict system performance. Water-quality issues must be evaluated, especially with respect to formation of clogging layers on basin bottoms or other infiltration surfaces, and to geochemical reactions in the aquifer. Clogging layers are managed by desilting or other pretreatment of the water, and by remedial techniques in the infiltration system, such as drying, scraping, disking, ripping, or other tillage. Recharge wells should be pumped periodically to backwash clogging layers. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s10040-001-0182-4.

Mating behavior of the rock catfish, Silurus lithophilus

The mating behavior of the rock catfish Silurus lithophilus (Siluriformes: Siluridae), a species endemic to the Lake Biwa system, was observed from May to July in 1989–1994 along the rocky shore of the lake's outlet, the Seta River. The mating behavior of S. lithophilus involved a certain behavioral sequence: “chasing,”“clinging,” and “enfolding” while “squeezing” by the male; and “circling” by the spawned pair. The mating behavior of this species was basically similar to that of S. biwaensis, but greatly different from that of S. asotus, which spawns in running water (in ditches). The mating behavior of S. lithophilus (and S. biwaensis) might have developed as an adaptation to lentic environments such as the shores of the large river or the lake.

Acidity Fluctuations at a Broadland Site in Norfolk

(1) In November 1970 the acidity of Calthorpe broad in Norfolk, and some adjacent ditches, changed abruptly from near-neutrality to just above pH 3. The entire fish community of the broad perished as did freshwater mussels and most aquatic macrophytes. There was a spectacular invasion by the acidophilous alga Tribonema minus. After a period of acute acidity the pH of free water returned to neutrality but similar fluctuations occurred in most years between 1971 and 1979. (2) These events were paralleled by improved drainage in surrounding farmland that left a perched water table in the area around the broad. This situation was maintained by dams during the winter but evaporation and seepage caused extreme falls in water levels during the summer. As a consequence, soil, which was shown to be rich in pyrites, was subjected to alternate drying and saturation. In agricultural contexts these conditions are known to lead to the oxidation of pyrite and the formation of sulphuric acid. (3) Treatment by the addition of lime in 1978 was successful in maintaining neutral water in the broad although the acidity of the water in nearby ditches continued to fluctuate. A number of plants and animals recolonized the broad in a fashion consistent with their dispersal mechanisms.

Infiltration of Soils as Affected by the Pressure and Water Content at the Time of Compaction

AbstractInfiltration rates, volume reduction, and bulk densities of soils were determined on soils as a function of compacting pressures and water content at the time of compaction.Maximum compaction generally occurred when the soils were packed at water contents near field capacity.When compacting loads were &lt; 1 kg/cm2 the minimum bulk densities occurred when soils had water contents of about one half field capacity, indicating that surface tension of water films in the soils plays a major role in cohesiveness and stabilization against compaction under these conditions.Compacting loads of 3.46 kg/cm2, at field capacity on sandy loams and finer textured soils, reduced infiltration rates to &lt; 0.1% of values obtained after these soils had been compacted when they were air dry. In a loamy sand soil this reduction was to about 1%.The low infiltration rates following compaction were increased by wetting and drying, although several cycles of wetting and drying did not raise the infiltration rate to the level observed before packing.Freezing and thawing cycles also increased the infiltration rates of previously compacted soils. Most of the change took place in the first freezing and thawing cycle.The large changes in infiltration rates using achievable levels of compaction at the “optimum” water contents indicate that compaction can play a major role in the management of water in ditches, reservoirs, furrows, and watersheds.

A New Picture Deep Among Mist-Shrouded Mountains

To our great delight we recently made a trip to Ke-hsin Brigade, K'e-tien Commune in Chung-hsiang hsien of Hupei Province to have a look at the beautiful picture which the brigade members had painted against the backdrop of deep, mist-shrouded mountains. Along the mountain slopes were neatly etched terraced fields. Blue sky was mirrored in various reservoirs. Clear water in the irrigation ditches threaded among the mountains. The valleys resounded with the roar of tractors and engines. Citing the tremendous changes the brigade had experienced over the past few years, the brigade members lashed out at Lin Piao's criminal acts in attacking and negating the Great Proletarian Cultural Revolution.

Seepage of leaching water into drainage ditches of unequal water level heights

The theory is developed, and numerical examples are worked out for the seepage of ponded water into equally spaced ditches in homogeneous soil overlying a barrier. Two general cases are solved: (a) unequal depth of water in the drainage ditches and (b) equal depth. For both (a) and (b) the problem is solved for zero depth of ponded water and for finite depth of ponded water; these solutions are quite different. Curves are supplied showing the surface inflow seepage velocity as it varies with distance from a ditch. Near ditches the seepage inflow rate is very high compared with that between ditches, which helps explain why, many times, crops do better when near ditches than when removed from them in reclaimed saline soil.