Assessment of Soil Physical Quality and Water Flow Regulation under Straw Removal Management in Sugarcane Production Fields

Removing sugarcane straw to increase bioenergy production can generate significant income to the industry. However, straw contributes to the regulation of soil functions and consequently supports the provision of ecosystem services, such as water flow regulation. Thus, straw removal may hinder the provision of these services, especially in mechanized sugarcane production systems, which have soil compaction problems due to machinery traffic. In this study, we assess a six-year experiment in Brazil with four rates of straw removal: 0 Mg ha−1 (TR), 5 Mg ha−1 (HR), 10 Mg ha−1 (LR), and 15 Mg ha−1 (NR) remaining straw. Using attributes, such as soil bulk density, porosity, water infiltration, runoff, saturated hydraulic conductivity and available water-holding capacity, as indicators of key soil functions, we calculated a soil-related ecosystem service (ES) index for water flow regulation provision. The ES index revealed that water flow regulation was low regardless of the straw management (0.56, 0.63, 0.64 and 0.60 for TR, HR, LR and NR, respectively). It can be a consequence of soil compaction caused by machinery traffic throughout the successive cycle, whose straw was unable to mitigate this issue. Thus, by the end of the sugarcane cycle (sixth ratoon), straw removal had little effect on soil physical and hydraulic indicators, and consequently had little impact on the provision of the soil-related ES associated with water flow regulation. Nevertheless, straw management should be planned to consider other functions and soil-related ES benefited by straw retention.

The Effects of Rehabilitation Treatments on Landscape Function Within a Softwood Plantation After Fire: Implications for Catchment Management

There is global interest in enhancing the ecosystem services provided by landscapes and catchments dominated by plantation (monoculture) forestry. Partial reversion of plantations to locally native species (reforestation) is one option. However, the ecological outcomes of this kind of plantation reversion are poorly known. The partial reforestation of a pine plantation (Pinus radiata D. Don 1836) in the Australian Capital Territory with native species following a wildfire provides a rare case study of the environmental consequences of such a reversion. We estimated changes in landscape functionality by measuring indices of water infiltration, nutrient cycling, and soil surface stability across five landscape-scale treatments after the 2003 Lower Cotter Catchment bushfire: (1) natural regeneration of a native forest burned in 2003, (2) burned pine plantation replanted to pines, (3) burned plantation replanted to native trees and shrubs, (4) burned plantation allowed to naturally regenerate, and (5) forest roads rehabilitated by planting native trees and shrubs. At 14 years after the fire, we found that the regenerating native forest had the highest indices of water infiltration, nutrient cycling, and soil surface stability. The burned pine plantation that was replanted to pines in 2005 had indices of functionality that were higher than the burned plantation areas that were either allowed to naturally regenerate to native eucalypt forest or were planted with native forest species. These two types of native forest rehabilitation treatments had only minor differences in functionality. The rehabilitated closed roads were the least functional. We found that a pine plantation at the closed canopy stage can supply regulating services of water infiltration, nutrient cycling, and soil surface stability comparable to a native forest at a similar stage postfire; however, a significant limitation of the plantation was its low ecosystem resilience. It required massive soil disturbance to replant postfire and long-term maintenance of an extensive unpaved road network. The active or passive rehabilitation of native forest is justified to improve the natural resilience to wildfire. However, this rehabilitation of a native forest following use as a pine plantation is a multidecade process in this relatively low-rainfall environment. Study Implications The 2003 Canberra bushfire destroyed the entire pine plantation at Lower Cotter Catchment, a water catchment in Australian Capital Territory, but also provided an opportunity to examine and quantify changes in ecosystem functions with different restoration treatments. Landscape Function Analysis, including three indices (water infiltration, nutrient cycling, and soil surface stability), was used in this study. Findings suggest that both native eucalyptus forests and pine plantations recovered to relatively high levels of functionality within just 15 years after the bushfire, compared with all other restoration treatments, but plantations of Pinus radiata are not resilient to wildfire from a commercial perspective. These results help to justify the controversial decision to restore the majority of the catchment with native species in 2005. However, long-term monitoring is needed to determine how long it will take for the replanted and natural regeneration treatments to approach the functionality of the native forest.

EVALUATION OF THE DESIGN OF RETAINING WALLS ON THE ROAD SUKABUMI (BAROS) - SAGARANTEN KM BDG 115+200

<p>The Sukabumi (Baros) – Sagaranten Km Bdg 115+200 road section which is located in Sukabumi Regency is a road section for the province of West Java. Because the road is always damaged due to being eroded by water infiltration in the rice fields that seeps into the road body area at that location and the soil at that location tends to be unstable based on the results of lab tests having a shear angle value of 4.99ᵒ and having a specific gravity of 17.45, then it is carried out analysis of the existing damaged retaining wall and the design of a new gabion-type retaining wall at that location. The gabion retaining wall building will be designed with 3 designs, the first using a stone volume of 13 m3, the second using a stone volume of 8 m3 and the third using a stone volume of 6.5 m3. Based on the results of the calculation analysis using Rankine theory, it was found that the existing retaining wall was unable to withstand the shearing force which got a check value of 1.18 which should have a value of SF &gt; 1.5, while the 3 gabion plan buildings got the appropriate SF value, namely against the overturning force, shear force and soil bearing capacity.</p>

PHYSICAL AND ENGINEERING PROPERTIES OF PEAT SOIL STABILIZED WITH THE ADMIXTURE OF CACO3+RICE HUSK ASH DUE TO WATER INFILTRATION FROM SURROUNDING AREAS

Peat is a type of soil with high organic content, very low bearing capacity, and high uneven settlement. Some methods to improve soil have been applied to peat in order to make it strong enough for civilization-building foundation situated on it. Peat stabilization is a method that is continuously developed considering that the cost it needs is lower and this approach is more environmentally friendly compared to other methods. The admixture of lime (CaCO3) and Rice husk ash, a new ecofriendly stabilizer material, has been applied to peat soil and showed a good result. However, in studies conducted previously, the effect of water infiltration from surrounding areas of soil was stabilized was not involved as variable influencing the change of parameter. Based on that, this laboratory study was carried out to model the real condition in the field when the stabilization is performed and to identify the physical and engineering changes of peat soil in the 10th, 20th, and 30th days of stabilization in its border and middle parts, with the percentage of material stabilizer 5%, 10%, 15% and 20% of the unit weight of the initial condition of peat. The result of laboratory test shows that the addition of admixture of lime (CaCO3) and rice husk ash can improve the physical and engineering properties of peat soil are stabilized. Water infiltration occurred on peat soil is stabilized has not affected the physical and engineering properties of the soil. It can be seen from the physical and engineering properties of the border and central parts of peat soil is stabilized that still have a similar value. It is assumed to be caused by CaSiO3 gel formed still needs a longer duration to become stable gel. However, in this initial study it was known that the more stabilizers added, made the better the parameters of the stabilized peat soil.

Evaluation of Infiltration Improvement and Surface Reduction Using Various Soil Conservation Techniques in Coffee Agroforestry Systems in Sumbermanjing Wetan

The uneven distribution and intensity of rain cause a shortage and excess of water in dry land farming. It appears that the problem of soil conservation in principle is the regulation of the relationship between rainfall intensity, infiltration capacity, and runoff adjustment. To improve the physical properties of the soil, and the hydrological function of the land use it cannot only be stressed on the coffee plant. Other factors such as soil surface management, such as providing organic matter, covering the soil surface with understory plants, making absorption holes, terraces, waterways and so on, can improve the hydrological function of the land. Rainwater management can be carried out through controlling surface runoff, harvesting rainwater, increasing soil infiltration capacity, managing soil, controlling evaporation and seepage, lining waterways. The use of silt pit parallel is considered quite effective because it is able to produce the lowest surface runoff and sufficient water storage. Silt pit parallel can produce 0.6% of rainfall into surface runoff and also can store water as much as 62.35% of the rainfall that enters the plot. The functions of a silt pit are to increase water infiltration into the soil. On dry land, silt pit functions as a place for harvesting rainwater and surface runoff. Based on the correlation regression test, the amount of surface runoff is closely influenced by the intensity of rain or rainfall.

IDENTIFIKASI BENCANA BANJIR KELURAHAN TLOGOSARI KECAMATAN PEDURUNGAN KOTA SEMARANG

ABSTRAK Bencana banjir di Kota Semarang sudah tak asing lagi bagi masyarakat Semarang, khususnya pada wilayah timur Kota Semarang, bencana banjir di Kota Semarang disebabkan beberapa faktor antara lain curah hujan yang tinggi, permukaan tanah yang lebih rendah dibandingkan permukaan air laut, dan banyaknya sampah yang tersumbat pada saluran drainase. Bencana banjir yang disebabkan oleh beberapa faktor tersebut berdampak buruk bagi Kota Semarang khususnya pada Kelurahan Tlogosari, Kecamatan Pedurungan, dampak dari bencana banjir tersebut mengakibatkan kerusakan pada jalan, kemacetan, dan dapat menyebabkan penyakit pada lingkungan di wilayah deliniasi di Kelurahan Tlogosari, Kecamatan Pedurungan. Perlu adanya penanganan untuk mengatasi bencana banjir di wilayah deliniasi Kelurahan Tlogosari, Kecamatan Pedurungan, seperti upaya melakukan pembangunan sistem pengendali banjir dan pada sistem drainase, dan pembangunan sumur resapan air pada setiap permukiman, serta melakukan konservasi secara berkala untuk sungai maupun sistem drainase di wilayah deliniasi Kelurahan Tlogosari, Kecamatan Pedurungan. Kata Kunci : Identifikasi; Banjir; Tlogosari ABSTRACT The flood disaster in Semarang City is familiar to the people of Semarang, especially in the eastern area of Semarang City, the flood disaster in Semarang City is caused by several factors, including high rainfall, lower land surface than sea level, and the amount of clogged garbage. on the drainage channel. The flood disaster caused by several of these factors had a bad impact on the city of Semarang, especially in Tlogosari Village, Pedurungan District, the impact of the flood disaster caused damage to roads, congestion, and could cause disease in the environment in the delineation area in Tlogosari Village, Pedurungan District. There is a need for handling to overcome flood disasters in the delineation area of Tlogosari Village, Pedurungan District, such as efforts to build a flood control system and drainage system, and build water infiltration wells in each settlement, as well as carry out periodic conservation of rivers and drainage systems in the delineation area. Tlogosari Village, Pedurungan District.Keyword: Identification;Flood; Tlogosari

Pengaruh Perubahan Pola Ruang Terhadap Tingkat Resapan Air - Studi Kasus di Kecamatan Arjawinangun Kabupaten Cirebon

The development of the city is very fast. Various socio-economic activities grow in line with the development of various human needs. The need for land to accommodate these various activities is difficult to avoid, so the city seems to be competing to build and consume the existing land. This condition has an impact on decreasing water absorption, thus threatening various disasters such as floods, the destruction of biodiversity, and drought, of course, the scarcity of clean water. Facing this phenomenon, the research examines the extent to which land use changes affect the level of water infiltration by calculating changes in the conservation index. This study takes the case in Arjawinangun Sub District. The selection of this location is solely due to the availability of data and the spatial plan that is currently being prepared whether it can become one of the parameters for changes in land use in the future.

Modeling Semiarid River–Aquifer Systems with Bayesian Networks and Artificial Neural Networks

In semiarid areas, precipitations usually appear in the form of big and brief floods, which affect the aquifer through water infiltration, causing groundwater temperature changes. These changes may have an impact on the physical, chemical and biological processes of the aquifer and, thus, modeling the groundwater temperature variations associated with stormy precipitation episodes is essential, especially since this kind of precipitation is becoming increasingly frequent in semiarid regions. In this paper, we compare the predictive performance of two popular tools in statistics and machine learning, namely Bayesian networks (BNs) and artificial neural networks (ANNs), in modeling groundwater temperature variation associated with precipitation events. More specifically, we trained a total of 2145 ANNs with different node configurations, from one to five layers. On the other hand, we trained three different BNs using different structure learning algorithms. We conclude that, while both tools are equivalent in terms of accuracy for predicting groundwater temperature drops, the computational cost associated with the estimation of Bayesian networks is significantly lower, and the resulting BN models are more versatile and allow a more detailed analysis.

A Mathematical Model for Transport and Growth of Microbes in Unsaturated Porous Soil

In this work, we develop a mathematical model for transport and growth of microbes by natural (rain) water infiltration and flow through unsaturated porous soil along the vertical direction under gravity and capillarity by coupling a system of advection diffusion equations (for concentration of microbes and their growth-limiting substrate) with the Richards equation. The model takes into consideration several major physical, chemical, and biological mechanisms. The resulting coupled system of PDEs together with their boundary conditions is highly nonlinear and complicated to solve analytically. We present both a partial analytic approach towards solving the nonlinear system and finding the main type of dynamics of microbes, and a full-scale numerical simulation. Following the auxiliary equation method for nonlinear reaction-diffusion equations, we obtain a closed form traveling wave solution for the Richards equation. Using the propagating front solution for the pressure head, we reduce the transport equation to an ODE along the moving frame and obtain an analytic solution for the history of bacteria concentration for a specific test case. To solve the system numerically, we employ upwind finite volume method for the transport equations and stabilized explicit Runge–Kutta–Legendre super-time-stepping scheme for the Richards equation. Finally, some numerical simulation results of an infiltration experiment are presented, providing a validation and backup to the analytic partial solutions for the transport and growth of bacteria in the soil, stressing the occurrence of front moving solitons in the nonlinear dynamics.

Mixed formulation for an easy and robust numerical computation of sorptivity

Sorptivity is one of the most important parameters for the quantification of water infiltration into soils. Parlange (1975) proposed a specific formulation to derive sorptivity as a function of the soil water retention and hydraulic conductivity functions, as well as initial and final soil water contents. However, this formulation requires the integration of a function involving the hydraulic diffusivity, which may be undefined or present numerical difficulties that cause numerical misestimations. In this study, we propose a mixed formulation that scales sorptivity and splits the integrals into two parts: the first term involves the scaled degree of saturation while the second involves the scaled water pressure head. The new mixed formulation is shown to be robust and well-suited to any type of hydraulic functions - even with infinite hydraulic diffusivity or positive air-entry water pressure heads - and any boundary condition, including infinite initial water pressure head, h → −∞.