Soil moisture dynamics under different land uses on karst hillslope in northwest Guangxi,China

Temporal and spatial dynamics of soil moisture are little known on karst hillslope with shallow soil in subtropical region. The objectives of this paper were (1) to investigate the temporal dynamics of soil moisture at depth of 0–10 cm under different land uses; and (2) to understand the relationship between mean and coefficient of variation (CV) of moisture contents on karst hillslope in northwest Guangxi, China. Soil moisture contents had a moderate variation (CV 17.5–30.3%) over an 8-month period and they had a significant difference among different land uses at the 0.01 level with a decreasing order: native scrubland > abandoned cropland and sloping cropland > economic forestland. There were higher mean and lower CV of moisture contents in rainy season than those in drought season. Mean and CV of moisture contents had a significant negative linear relationship except in abandoned cropland with higher soil and vegetation heterogeneity. This suggested that spatial variability of soil moisture within sampling sites would decrease when soils were wet and increase when soils were arid. Compared with rainy season, more soil samples may be needed and the interval for sampling should be shortened in drought season. Such information provided some insights to better understand the dynamics and variability of soil moisture at a larger scale in karst region of southwest China.     

Short-term variability of water quality parameters in two shallow estuaries of North Carolina

We quantified the effects of nutrient loading following precipitation events (≥ 1.25 cm) in 2 tidal creeks varying in size and anthropogenic input during the winter and summer seasons of 1996. Several water quality parameters were repeatedly measured in the water column every 3 h for several days after each event (4–5 per season). Total nitrogen (TN) and total phosphorus (TP) behaved nonconservatively with salinity and appeared as pulsed additions, occasionally doubling within 1 to 2 tidal cycles following significant rain events. Average values for TN, TP, and chlorophylla were 10–15 μM, <4 μM, and <7 μg l⁻¹, respectively for winter events and 30–35 μM, >4 μM, and ≥ 7 μg l⁻¹, respectively for summer events. However, response times were variable, depending on the magnitude and duration of the event as well as temperature. Chlorophylla biomass often increased after nutrient additions, especially in the summer when increased nutrient loading took place. Dissolved silica (DSi) behaved conservatively with salinity; low values were observed at high tide and vice versa. Average DSi ranges for winter and summer events were 5–45 μM and 10–85 μM, respectively. DSi range values increased proportionally with the amount of freshwater loaded into the system. Recovery times for salinity were usually greater than the recovery times for nutrients. Dissolved oxygen displayed a diel pattern, increasing after daytime productivity and decreasing during nighttime. In conclusion, each rainfall event was unique and responses were variable depending upon rainfall history, seasonality, and the duration and intensity of the rainfall event. Several other variables, such as water viscosity, percolation rates, and evapotranspiration rates which were not quantified in this study, could have also explained parameter responses.     

Soil salinity and sodicity in a shrimp farming coastal area of the Mekong Delta,Vietnam

Soil salinity and sodicity are environmental problems in the shrimp farming areas of the Cai Nuoc district, Ca Mau province, Vietnam. In 2000, farmers in the district switched en masse from rice cropping to shrimp culture. Due to recent failure in shrimp farming, many farmers wish to revert to a rotational system with rice in the wet season and shrimps in the dry season. So far, all their attempts to grow rice have failed. To assess soil salinity and sodicity, 25 boreholes in shrimp ponds were analysed in four consecutive seasons from 2002 to 2004. The results showed that soil salinity was quite serious (mean EC_e 29.25 dS m⁻¹), particularly in the dry season (mean EC_e 33.44 dS m⁻¹). In the wet season, significant amounts of salts still remained in the soil (mean EC_e 24.65 dS m⁻¹) and the highest soil salinity levels were found near the sea. Soil sodicity is also a problem in the district (exchangeable sodium percentage range 9.63–72.07%). Sodicity is mainly a phenomenon of topsoils and of soils near the sea. Both soil salinity and sodicity are regulated by seasonal rainfall patterns. They could together result in disastrous soil degradation in the Cai Nuoc district.     

Spatial and Seasonal Patterns of Salinity in a Large and Shallow Tropical Estuary of the Western Caribbean

Salinity profiles and meteorological data were analyzed during February, May, and September 2006 in Chetumal Bay, a large, shallow estuary of the Western Caribbean. Local meteorological conditions revealed three seasons: (1) a dry season (March–May); (2) a wet season (June–October); and (3) the nortes season, with northerly wind events (October–February). During the nortes and wet seasons, salinity ranged between 13 and 16 psu, and salinity was highest in the dry season, ranging between 18 and 22 psu over most of the area; a strong stratification and a significant contribution of salty water characterized this season. Strong horizontal gradients were observed near Rio Hondo during the three seasons. Deep and narrow peculiar bathymetric features called the pozas showed a strong stratification and a relatively high salinity. The northern part of Chetumal Bay and probably the entire system are far from being homogeneous.     

Yangtze Delta, China: Taihu lake-level variation since the 1950s, response to sea-level rise and human impact

 Hydrological records collected from water gauge stations since the 1950s demonstrate that the Taihu lake level is rising. The average rate of the lake-level rise is 0.4–1.1 mm/year during the non-flood season, resulting directly from a rise in sea level. High rates of 3.0–5.0 mm/year of rise are even recorded during the wet season. This indicates increasing human activities such as reclamation, sluicing and embanking, which significantly hinder the expulsion of extra lake water to the coast shortly after a rainfall. Generally, the lake level of the western inlet is higher than that of the eastern outlet. However, the lake-level difference between the west and east has been diminished annually from ∼10–15 cm in the 1950s to <3 cm at the present time. During non-flood seasons, the lake-level difference even appears to be reversed, indicating a retrogression of the lake flow from east to west. It is predicted that the Taihu drainage basin will lose much of its natural water-expelling ability in the next 50 years as the sea level continues to rise, and retrogression will likely occur during the flood season in the near future. Received: 13 March 1998 · Accepted: 21 July 1998     

Assessing changes in the rainfall regime in Nigeria between 1961 and 2004

The study assessed changes in the rainfall regime in Nigeria between 1961 and 2004 in terms of (a) absolute seasonality—the length of dry and wet season; (b) relative seasonality—rainfall contrast during the year; (c) number of rainfall maxima and minima; and (d) timing of rainfall maxima and minima. Trends in the mean monthly surface locations of the Inter-tropical Discontinuity (ITD) were also examined as a prominent factor of the rainfall regime. Changes in the regime were examined over four time slices: 1961–1971, 1972–1982, 1983–1993 and 1994–2004. The results show that, in the area of single rainfall maximum regime, the length of the wet season has increased from 4 months (in 1961–1971) to 5 months (since 1972–1982). The rainfall relative seasonality has consistently been ‘most rain in 3 months or less’. The rainfall maxima still indicate single rainfall maximum but shift in the peak from August to July. Rainfall during the months of June to September appears to have witnessed declining trends over the first three time slices. The last time slice however indicates trends towards a wetter condition. For the area of double maxima rainfall regime, the length of the wet season has consistently been 8 months. The rainfall relative seasonality has consistently been ‘rather seasonal with a short drier season’. The rainfall maxima and minima still indicate double rainfall maxima with August as the month of the minimum but shift in the primary peak from July to September. The northward latitudinal distance of the surface location of the ITD from the equator indicates significant upward trends during the months of May to September only and for a period of 1983–2000. The trend results of the ITD appears to account for most of the observed changes in the rainfall regime in Nigeria.     

Mangrove zonation in the dry life zone of the Gulf of Fonseca, Honduras

The structural attributes and zonation patterns of mangrove forests in a dry environmental setting were evaluated in relation to gradients of soil resources, soil regulators, and hydroperiod between October 2000 and August 2001 in the Gulf of Fonseca, Honduras. Transects perpendicular to the edge of tidal channels were established at four mangrove sites, each sectioned into three mangrove zones (fringe, transition, and scrub) based upon distinct tree-height gradients. Porewater sulfide concentrations among zones were normally below levels of detection (<0.03 mM) and mean redox values ranged from 163.4±9.9 to −42.4±15.8 mv, indicating slightly reducing conditions in all zones. Mean porewater NO_x ⁻ and PO₄ ³⁻ concentrations were not significantly different among zones and ranged from 3.3±0.5 to 4.5±0.4 μM and from 0.05 ±0.02 to 0.18±0.04 μM, respectively. Soil nitrogen concentrations were 1–3 mg g⁻¹ in all zones, and mean nitrogen:phosphorus atomic ratios were <20 (range: 12.9–14.9), indicative of fertile wetland soils. Mean basal areas were significantly different among mangrove zones (fringe > transition) and were coupled with differences in height within species and zones.Avicennia germinans occupied areas with higher elevations associated with higher salinities ranging from 80 to 140 g kg⁻¹ in the dry season.Rhizophora mangle dominated lower elevations where salinities ranged from 38 to 57 g kg⁻¹ in both the dry and wet seasons. Spatial analysis on mangrove seedlings along transects confirmed that seedling distribution along the intertidal profile was statistically correlated with conspecific adults, indicating that survival and growth of seedlings in different intertidal locations are closely matched to canopy membership. The sharp transition (<100 m) in forest structure and distribution of mangrove species along the intertidal zone of subhumid coastal environments demonstrate common zonation patterns where species distribution and species-specific habitat suitability are mediated closely with tolerance to soil regulators (high soil salinity) rather than resource availability.     

Effects of saline water irrigation on soil properties in northwest China

Due to the lack of freshwater, highly saline groundwater was the main irrigation source in the last few decades in the Minqin Basin, which is in northwest China. The study evaluates the effects of salt accumulation on the soil physical–chemicals properties. Undisturbed and disturbed soil samples were taken from the experiment site, which was irrigated with saline water at a concentration of 0.8, 2 and 5 g L⁻¹ (coded later as C₀₈, C₂ and C₅). Undisturbed soil samples, at depths of 0–45 and 45–60 cm were taken to determine the water retention curve (WRC). Moreover, in the same place, another set of undisturbed soil samples were taken to determine the porosity and pore-size distribution (PoSD). From the WRC, the water-holding capacity of the soil was estimated. Disturbed soil samples at depths of 0–20, 0–45, 45–60 and 80–100 cm were taken to determine the index of aggregates stability in water (IC). The electrical conductivity of the saturated paste (EC_e) was determined at depths of 0–30, 30–60 and 60–90 cm, during the irrigation season on C₀₈, C₂ and C₅ treatments. The results show that the total porosity and the index of aggregates stability in water decrease with the increasing salinity of irrigation water, and the EC_e increases with the increasing salinity of irrigation water especially in the surface soil. The water-holding capacity (WHC) of soil also increases with the increasing salinity of irrigation water.     

Spatial variability of soil moisture at typical alpine meadow and steppe sites in the Qinghai-Tibetan Plateau permafrost region

Permafrost degradation has the potential to significantly change soil moisture. The objective of this study was to assess the variability of soil moisture in a permafrost region using geostatistical techniques. The experiment was conducted in August 2008 in alpine steppe and meadow located in the Qinghai-Tibetan Plateau permafrost region. Four soil depths (0–10, 10–20, 20–30 and 30–40 cm) were analyzed using frequency domain reflectometry, and sampling made of 80 points in a 10 m × 10 m grid were sampled. Soil moisture was analyzed using classical statistics to appropriately describe central tendency and dispersion, and then using geostatistics to describe spatial variability. Classical statistical method indicated that soil moisture in the permafrost region had a normal distribution pattern. Mean surface soil moisture in alpine meadow was higher than that in alpine steppe. The semivariograms showed that soil moisture variability in alpine cold steppe was larger than that in alpine meadow, which decreased with depths. Nugget values in alpine steppe were low (0.1–4.5), in contrast to alpine cold meadow. Soil moisture in alpine steppe had highly structured spatial variability with more than 93.4% spatial heterogeneity, and the range decreased with depth. Soil moisture content in alpine cold meadow had a moderate spatial dependence with a range of 51.3–169.2 m, increasing with depth.     

小降雨事件对土壤水分及植物水势空间差异性的影响

本文以云南省蒙自市断陷盆地高原面上典型封闭式岩溶洼地小流域为研究对象,研究小降雨事件对土壤水分及植物水势的影响。结果表明:（1）在研究区内小降雨事件一般只能补给10 cm以上的土壤,因此在旱季（强降雨事件发生前）,土壤水分随着深度的增加整体呈变小的趋势;受洼地地形影响,整个土壤剖面（0 ~ 80 cm）的土壤水分存在从坡顶到洼地底部逐渐增加,苹果树叶水势逐渐升高的现象;受地质背景的影响,土石质坡地平均土壤水分比石质坡地土壤水分高2.67%,相对应的土石质坡地苹果树受干旱胁迫的程度要低于石质坡地。（2）通过观测对比发现,8天内12次的小降雨事件可以使0~10 cm土壤水分整体上略有升高,但并未能完全改变0~10 cm土壤水分洼地底部大于两侧坡地,而土石质坡地高于石质坡地的特征。（3）小降雨事件虽然只能补给0~10 cm的土壤水分,但由于坡地地区苹果树根系分布较浅（5~30 cm）,部分浅层分布的苹果树根系已能吸收到水分,另一方面小降雨事件具有降温、增湿,减少太阳辐射的作用,可以减小苹果树蒸腾作用,从而降低苹果树叶水势,因此推测小雨事件可以明显减轻苹果树受干旱胁迫的程度      

The influence of marine inflows on the chemical composition of groundwater in small islands: the example of the Cyclades (Greece)

 Marine contamination of groundwater may be caused by seawater intrusion and by salt spray. The role of both processes was studied in the Cyclades archipelago on four small islands (45–195 km²) whose aquifers consist essentially of fractured, weathered metamorphic rocks. Annual rainfall ranges from 400 to 650 mm and precipitation has high total dissolved solids contents of 45–223 mg l^–1. The chemical characteristics of the groundwater, whose salinity is from 0.4 to 22 g l^–1, are strongly influenced by seawater intrusion. However, the effect of atmospheric input is shown in certain water sampling locations on high ground elevation where the dissolved chloride contents may attain 200 mg l^–1. Received: 14 November 1995 · Accepted: 9 September 1996     

Diurnal soil water dynamics in the shallow vadose zone (field site of China University of Geosciences,China)

Because of the relatively low soil moisture in arid or semi-arid regions, water vapour movement often predominates in the vadose zone and affects the partitioning of energy among various land surface fluxes. In an outdoor sand bunker experiment, the soil water content at 10 and 30 cm depth were measured at hourly intervals for 2.5 days during October 2004. It was found that the soil moisture reached the daily maximum value (5.9–6.1% at 10 cm and 11.9–13.1% at 30 cm) and minimum value (4.4–4.5% at 10 cm and 10.4–10.8% at 30 cm) at midday (0–1 p.m. for 10 cm and 2–3 p.m. for 30 cm) and before dawn (2–3 a.m. for 10 cm and 4–5 a.m. for 30 cm), respectively. The modified HYDRUS-1D code, which refers to the coupled water, water vapour and heat transport in soil, was used to simulate the moisture and water vapour flow in the soil. The numerical analyses provided insight into the diurnal movement of liquid water and water vapour driven by the gradients of pressure heads and temperatures in the subsurface zone. The simulated temperature and water content were in good agreement with the measured values. The spatial–temporal distribution of liquid water flux, water vapour flux and soil temperature showed a detailed diurnal pattern of soil water dynamics in relatively coarse sand. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Phytoplankton Interannual Variability at Cassino Beach, Southern Brazil (1992–2007), with Emphasis on the Surf Zone Diatom Asterionellopsis glacialis

A long-term study (monthly sampling, 1992 to 2007) was conducted in the surf zone of Cassino Beach, Southern Brazil, in order to detect possible natural and/or anthropogenic disturbances. Surface water temperature (6–29°C) was the only parameter with predictable seasonal variation; salinity (14–38) was inversely related to rainfall (3.1–485.2 mm month⁻¹) and low values followed extreme precipitation periods in 1997/1998 and 2002/2003 (El Ni?o years). Asterionellopsis glacialis and chlorophyll a presented high concentrations and peak frequency until 1998, when an intense mud deposition occurred with concomitant extreme rainfall. It affected the surf zone and beach, changing the hydrology and dissolved inorganic nutrient availability. Six phytoplankton species groups were recognized with distinct responses to this mud deposition. We conclude that large-scale climatic changes, like El Ni?o Southern Oscillation, in conjunction with human activities significantly altered the phytoplankton ecology of the highly dynamic Cassino Beach surf zone.     

黄土丘陵小流域地形和土地利用对土壤水分时空格局的影响

采用1982～1985年和2002年两个时段的定点观测数据,系统分析了小流域尺度地形和土地利用类型对土壤水分时空格局的影响.结果表明:1)土壤水分变化特征为所有年份农地土壤水分都最大,灌木林地和荒草地较低,林地居中;不同坡向间以阴坡土壤水分最大;而不同坡位间以坡中部土壤水分最大.受降雨和植被耗水的影响,所有土地利用类型中土壤水分在整个生长期表现为降低型.2)在年尺度上表现为干旱年份土地利用类型和坡向对土壤水分的影响较大;而在湿润年份,其影响程度减弱;坡位在干旱和湿润年份对土壤水分的影响都较小.湿润年份,降雨量的增大弱化了地形和土地利用类型对土壤水分时空格局的影响;而干旱年份正好相反.3)在季节尺度上表现为在生长季节的中后期,土壤水分的变异格局主要受坡向影响;而在生长季节的中期,主要受土地利用类型影响;坡位在整个观测时段内影响都较小.4)在不同土壤层次方面特征为土地利用类型对0～20em层次影响较小,而对其他4个深度较大的层次(20～100cm)影响较大,并且5个层次中以40～60cm层次的差异最大;坡向对5个层次土壤水分的变异格局均有明显影响,并呈现随着深度的增加,其影响减弱的趋势;坡位对5个层次的土壤水分变异格局影响均较小.     

Nitrogen isotope indicators of seasonal source variability to groundwater

 A nitrogen isotope study of soil water and groundwater in southern Indiana, USA, in 1991–1992 demonstrated considerable variations in nitrate degradation processes compared to an earlier investigation in 1986–1987. Although N-fertilizers were applied in May 1991, the δ¹⁵N values in soil water decreased in February 1992, indicating its delayed release into the system after substantial rainfall. The δ¹⁵N values of groundwater decreased from +12.3‰ in November 1991 to +11.3‰ in February 1992, and to +7.5‰ in March 1992. The increased residence time of nitrate in the soil resulted in increased denitrification, ammonia volatilization and plant uptake, and reduced threat to the groundwater quality. The 1986–1987 study in the area reported that excessive rainfall during the summer rapidly transported the nitrate to deeper horizons and drastically reduced volatilization and microbial reduction of nitrate, thus increasing the immediate threat to the groundwater quality in the area. The present study demonstrated that nitrogen isotopic signatures can be used to determine the effects of local soil type, rainfall, and land-use practices on the fate of nitrate in the subsurface. Received: 18 February 1997 · Accepted: 17 June 1997     

Effects of sediment slurry enrichment on salt marsh rehabilitation: Plant and soil responses over seven years

In deltaic marshes, mineral sediment promotes positive elevation change and counters subsidence and sea level rise. In many such marshes sediment deficits result in wetland loss. One new way to address sediment deficiency is to supply marshes with sediments in a slurry that deposits the sediment in a thin layer over a large area. The long-term effects of this strategy are poorly understood. In a rapidly submerging,Spartina alterniflora salt marsh, we tested how different amounts of sediment ameliorated the effects of sea level rise and subsidence over 7 yr (1992–1998). Sediment slurry enrichment likely affected plants and soils by two mechanisms. It increased elevation and soil bulk density, leading to increased plant vigor and soil condition. These effects were long lasting, such that by 1998 areas receiving moderate amounts of sediment (5–12 cm relative elevation) had better plant vigor and soil condition compared to areas not receiving sediment (55% cover versus 20%; bulk densities of 0.4–1.0 g cm⁻³ versus 0.2 g cm⁻³; 0 mM hydrogen sulfide versus > 1.0 mM). The sediment slurry also had high nutrient content, which resulted in a pulse of growth, especially in areas receiving the most sediment (areas > 12 cm relative elevation initially had >90% cover and canopy heights >1.6 m). This nutrient-induced growth spurt was short lived and faded after 3 yr, at which point the long lasting effects of increased elevation probably became the dominant factor promoting plant vigor and soil condition. Moderate levels of sediment generated the most beneficial and long lasting effects to the vegetation and soils. This degree of sediment slurry addition countered the effects of subsidence and sea level rise, but not so much as to surpass the intertidal position to whichS. alterniflora is best adapted.     

Rainfall as a trigger of shallow mass movements. A case study in the Dolomites, Italy

 The article presents results of regional analysis on a historical basis correlating the occurrence of shallow mass movements and disruptive events in time with precipitation trends. For the latter, different time-spans have been considered in an attempt to find the most typical ones which might have triggered landslides. Research was carried out in the 850 km² wide basin of the River Cordevole in the Dolomites (NE Italy). Data concerning slope movements and floods, which have affected the area since the last century, were collected. Events which took place after 1920 have been correlated with the significant pluviometric events recorded. In spite of the regionally high variability of both geological conditions and spatial distribution of precipitation, three types of typical pluviometric trends related to an effective rainfall period of 15 days and to a peak rainfall of 24–48 h preceding the onset of the movements were identified. Received: 1 November 1996 · Accepted: 25 June 1997     

科尔沁沙地土壤水分动态分析及其概率密度函数模拟

基于Laio土壤水分动态随机模型(Laio模型),利用2006-2010年5~9月土壤水分连续监测数据及日降水资料,分析科尔沁沙地固定沙丘和沙质草地生长季根系层土壤水分动态及其与降水格局的关系,研究点尺度土壤水分概率密度函数,并对Laio模型涉及的13个参数进行了敏感性分析。结果表明:① 研究区年降水的季节分配极不均匀,主要集中在4~10月的生长季,占全年降水量的93%;0~5 mm降水事件占全年降水事件的73%,但其降水量只占全年降水量的25%;降水间隔期以0~10 d为主,占全年无降水期的38%,其频数最高,占全年间隔期频数的87%。② 固定沙丘和沙质草地根系层厚度分别为0~100 cm和0~70 cm,沙质草地根系层土壤水分显著高于固定沙丘;两类沙地7月份的土壤水分都显著高于生长季其他月份。③ 两类沙地生长季根系层土壤水分均服从正态分布;通过Laio模型得到了两类沙地生长季根系层土壤水分概率密度函数p(s),其峰值及峰值出现的位置和峰的阔度均与观测结果很接近,说明Laio模型能对科尔沁沙地土壤水分概率密度函数进行较好的模拟。④ Laio模型涉及的13个参数中,对p(s)最为敏感的参数是降水频率λ、平均降水量α、最大蒸散量E_max、水分胁迫点s*和凋萎系数s_w,主要影响p(s)曲线的峰值。     

Comparison of 1982–1983 and 1997–1998 El Niño effects on the shallow-water fish assemblage of the Patos Lagoon estuary (Brazil)

Meteorological impacts of El Niño events of 1982–1983 and 1997–1998 were observed in locations throughout the world. In southern Brazil, El Niño events are associated with increased rainfall and higher freshwater discharge into Patos Lagoon, a large coastal lagoon that empties into the Atlantic Ocean. Based on interdecadal meteorological and biological data sets encompassing the two strongest El Niño events of the last 50 yr, we evaluated the hypothesis that El Niño-induced hydrological changes are a major driving force controlling the interannual variation in the structure and dynamics of fishes in the Patos Lagoon estuary. High rainfall in the drainage basin of the lagoon coincided with low salinity in the estuarine area during both El Niño episodes. Total rainfall in the drainage basin was higher (767 versus 711 mm) and near-zero salinity conditions in the estuarine area lasted about 3 mo longer during the 1997–1998 El Niño event compared with the 1982–1983 event. Hydrological changes triggered by both El Niño events had similar relationships to fish species composition and diversity patterns, but the 1997–1998 event appeared to have stronger effects on the species assemblage. Although shifts in species composition were qualitatively similar during the two El Niño events, distance between El Niño and non-El Niño assemblage multivariate centroids was greater during the 1996–2000 sampling period compared with the 1979–1983 period. We provide a conceptual model of the principal mechanisms and processes connecting the atmospheric-oceanographic interactions triggered by the El Niño phenomena and their effect on the estuarine fish assemblage.     

Relationship between the effective diffusion coefficient of soil radon and groundwater recharge in semi-arid areas

Herein, the relationship between soil radon behavior and groundwater recharge in the town of Hosha, a semi-arid area of Jordan is explored. The annual rainfall average in this area is between 60–100 mm year⁻¹. Soil radon concentration levels, using CR-39 detectors, have been measured at several depths. Nine sampling sites on a hill slope, in the summer and winter 2006 were chosen. Other soil parameters such as moisture, soil type and porosity were also measured. Correlation between the latter and the calculated effective diffusion coefficients, based on a linear approximation, was done in order to explore water movement. A weak correlation between the soil radon concentration and water recharge in this particular semi-arid area is observed. The results show that water recharge takes place vertically, i.e., water moves downward and in one of the nine sampling sites this movement seems to be more rapid compared to the other sites.