Abstract In the Highlands of Northern Ethiopia soil and water conservation (SWC) practices, including construction of check dams in gullies, have been widely implemented for the last three decades. Despite this extensive installation of check dams, their effects on runoff response are not well understood as compared to those of other SWC practices. Hence, this study examines the effects of check dams on runoff response in gully channels. 90 degree V-notch weirs were installed to measure a wide range of runoff discharges at the upper and lower sections of five gully reaches: two channel cut in sandstone (a gully with check dams and vegetation (SCV) and an untreated gully (S)) and three cut in limestone (an untreated gully (L), a gully with check dams but no vegetation (LC) and a gully with check dams and vegetation (LCV)). Automatic sensors were installed to monitor runoff depth during two rainy seasons (29/08/14 – 17/09/14 and 24/7/15 – 14/09/15). All runoff characteristics at the lower section of each gully reaches were calculated for a gully reaches length of 50 m. In the sandstone area, the results show longer lag times of runoff to reach the lower section of the channel reach in the treated gully (SCV) compared to the untreated gully: difference in time lag equal lag to production of runoff equals 51% for runoff initiation, 61% for peak runoff and 44% for runoff end. An increase of hydraulic roughness by check dams and water transmission losses in deposited sediments are responsible for the delay of runoff to reach the lower part of the gully channels. In the limestone area, different time lags were recorded in different gully reaches regardless of the treatment effects (lag to runoff initiation, lag to peak flow and lag to runoff end were larger at LC, L and LCV, respectively). The reduction of peak runoff discharge between the upper and lower gully sections was larger in the gullies with check dam and vegetation (8–17%) than in gullies without treatment (5–6%). Reduction of runoff volume between these 2 gully sections was also larger in treated gullies than in untreated gullies: i.e. 18%, 9% and 8% in SCV, LCV and LC, respectively while it was only 4% in S and 6% in L. This study shows that the implementation of check dams combined with vegetation reduced peak flow discharge and runoff volume as large sections of runoff infiltrated in the sediments deposited behind the check dams. As gully check dams are implemented in a large areas of the North Ethiopia Highlands, this contributes to groundwater recharge and increased river base flow.

https://biblio.ugent.be/publication/8518957/file/8518969.pdf

Effects of check dams on runoff characteristics along gully reaches, the case of Northern Ethiopia

How does land use/cover influence gully head retreat rates? An in situ simulation experiment of rainfall and upstream inflow in the gullied loess region, China

Kedong County is typical of the black soil region of northeast China in being highly susceptible to accelerated soil erosion by gullying. Using data sourced from Corona satellite imagery for 1965, SPOT5 for 2005 and GF-1 for 2015, the spatial distribution of gullies in the research area was mapped. Land use data for 1965, 2005 and 2015 were obtained from the topographic map of 1954, and from Landsat images for 2005 and 2015. Over the last 50 years, the extent of gully erosion in the study area has increased markedly, most notably on cultivated land, while gully density rose from 2,756.16 m²/km² to 14,294.19 m²/km². Cultivating land on slopes, especially on slopes greater than ~4 degrees, may rapidly aggravate gully erosion. The greatest increases in gully density occurred in situations when cultivated land and other / degraded land were transformed, which gully erosion density increased by 49,526.69 m²/km². Other / degraded land is the most vulnerable land in the study area, with the highest gully erosion density. In these cases, gully density initially increases and, although the ‘Grain for Green’ project has been implemented, gully erosion density has not always declined in the recent past.

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Effect of Land Use Change on Gully Erosion Density in the Black Soil Region of Northeast China From 1965 to 2015: A Case Study of the Kedong County

Because soil erosion is a primary cause of land degradation globally, it has received increasing attention in food production regions, such as the Chernozem region of Northeast China. This study assessed soil quality under soil erosion degradation using a novel optimal data set (ODS) approach and a comparative minimum data set (MDS) approach to derive soil quality indices (SQIs) within an agricultural watershed in Heilongjiang Province, China. The selection of SQIs was contingent on 15 physical, chemical, and microbial properties measured at 52 grids. Soil erosion rates were determined using the Cs‐137 technique. Results showed that SQIs derived from the ODS and MDS approaches were strongly correlated (r = 0.91, p < 0.01). However, soil quality inferred by SQIs varied significantly between erosion and deposition sites, namely, increasing from upstream to midstream to downstream areas. Changes in SQIs and erosion rates exhibited spatially opposing trends, reflecting the impact of soil erosion on soil quality, which was also confirmed by comparing representative soil properties at erosion and deposition sites. The ODS approach using the optimal fingerprinting factor screening procedure of the composite fingerprinting approach is a cause‐related method that uses a relatively strict indicator selection procedure, which mainly includes sample groupings, Kruskal–Wallis H test, discriminant function analysis, and conservative behaviour tests of factors. Thus, it can theoretically obtain more reliable results compared to MDS. Further studies are nevertheless needed to assess the feasibility of this novel approach in other cases.

A novel optimal data set approach for erosion‐impacted soil quality assessments—A case‐study of an agricultural catchment in the Chernozem region of Northeast China

The soil of the Loess Plateau is highly susceptible to erosion due to its distinct loess structure with poor water stability and disintegrates easily. Previous research has focused on improving soil strength without considering stability and ecological performance. Comprehensive improvements may be achieved through the use of cross-linked polymers (CLPs), but their effect on loess structure remains unclear. In the present study, we investigate the use of CLPs as a new organic soil stabilizer to improve soil aggregate stability. To determine the effect of CLPs on the stabilization of loess, a series of indoor tests was conducted to assess unconfined compressive strength, water stability, soil-water characteristics, and plant height. The stabilization mechanism was analyzed by comparing the microstructure, mineral composition, and features of functional groups of loess before and after treatment. The results showed that, compared with untreated loess, the unconfined compressive strength and anti-disintegration property of treated loess were significantly increased. The water retention capacity was improved, and the germination rate and growth of plants were promoted. Microscopic analysis showed that the use of CLPs did form new minerals in the loess or change the functional groups, rather, CLPs improved the microstructure, reduced the total volume of pores, and increased the degree of soil compaction. Finally, the practical application of CLPs was studied through a field test. The results demonstrated that loess hillslope erosion was effectively controlled by CLPs. Under the same erosive conditions, the slope surface treated with CLPs was more intact than the untreated slope surface. Our findings provide new strategies regarding the application of CLPs as soil stabilizers to control loess erosion and promote vegetation restoration.

/pdf/a-cross-linked-polymer-soil-stabilizer-for-hillslope-2bi795frjp.pdf

A Cross-Linked Polymer Soil Stabilizer for Hillslope Conservation on the Loess Plateau

Vegetated earth bund has been widely established to prevent soil erosion of farmland with the slope of 3–5° in Mollisols region of Northeast China. However, a well-adapted vegetation with greater erosion-control and higher economic benefit has not been determined. Here, an artificially simulated rainfall experiment with rainfall intensity of 25 mm h−1 was conducted on plots with eight kinds of earth bund (six vegetated earth bunds, one naturally grass-covered bund and one artificially bare bund) to investigate the runoff and soil loss process. The economic income of six vegetated earth bunds was also evaluated. The results showed that vegetation growing on earth bund reduced surface runoff and soil loss by 15.3–62.5% and 79.4–93.8%, compared to the bare bund, respectively, of which Medicago sativa, Rheum rhaponticum, Corylus heterophylla and Acanthopanax senticosus showed higher runoff and sediment reduction benefits than natural grass. Surface runoff and soil loss were significantly affected by the diverse community (P   0.05). Furthermore, compared to the average farmland economic benefits, Corylus heterophylla, Ribes nigrum, Acanthopanax senticosus and Physalis peruviana improved economic benefits by 1.1–9.9 times, while Rheum rhaponticum and Medicago sativa decreased economic benefits by 22.5% and 32.5%, respectively. Corylus heterophylla and Acanthopanax senticosus with Medicago sativa are highly recommended for controlling soil erosion of earth bund and increasing economic income. Our results provide a scientific reference and technical support for optimizing vegetation measures of slope farmland in Mollisols region of Northeast China.

The role of vegetation on earth bunds in mitigating soil erosion in Mollisols region of Northeast China

The effectiveness of selected vegetation communities in regulating runoff and soil loss from regraded gully banks in the Mollisol region of Northeast China

A two-dimensional information measurement method for a farmland erosion groove based on a non-aerial photograph of an unmanned aerial vehicle belongs to the technical field of water and soil loss monitoring. The invention aims to solve the problem that the existing map-based measurement methods for erosion groove area have a larger error. Based on a photograph from an unmanned aerial vehicle, withthe help of the known linear width information of ground-object around the erosion groove, the two-dimensional information measurement method calculates the proportional relationship between a distance in the photograph and an actual distance without measuring an acquired ground coordinate system by the unmanned aerial vehicle aerially, thereby avoiding arrangement of control points, aerial survey flight and photogrammetric software post-treatment, reducing manpower and material resources in field and internal works, and improving the efficiency. By measuring the distance of the width and thelength of the erosion groove in the photograph and converting the distance into the actual distance according to the proportional relationship, the method rapidly obtains the width and length information of the erosion groove, and then calculates the erosion groove area. The method of the invention is mainly used for measuring two-dimensional information of the farmland erosion groove.

Two-dimensional information measurement method for farmland erosion groove based on non-aerial photograph of unmanned aerial vehicle

e16084 Background: Recently, immunotherapy combined with trastuzumab and chemotherapy have been recommended by the clinical guidelines of many countries as the first-line treatment for advanced HER2-positive G/GEJ adenocarcinoma. Combining chemotherapy with tislelizumab and trastuzumab in the neoadjuvant/adjuvant setting may benefit patients with locally advanced, resectable HER2-positive GC/GEJC. Methods: This study is a multicenter, single-arm, open-label phase 2 study (NCT04819971). Patients with histologically confirmed cT2-4NxM0 or cTxN+M0, (TNM 8th edition), resectable gastric adenocarcinoma are eligible for this study. Neoadjuvant therapy will be administered for four cycles. The patients will receive tislelizumab and trastuzumab for 1 cycle (Q3W), followed by tislelizumab and trastuzumab combined with DOS (Docetaxel + Oxaliplatin + S-1) for 3 cycles (Q3W). Surgery is planned 4-6 weeks after preoperative treatment. Patients who have complete surgical resection will receive adjuvant therapy starting within 4–6 weeks after surgery for 6 cycles (three cycles of tislelizumab and trastuzumab combined with DOS regimen, followed by 6 weeks of tislelizumab and trastuzumab for 6 cycles. The primary endpoint was pathological complete response rate (pCR). Secondary endpoints included R0 resection rate, 1-year and 2-year event-free survival (EFS), overall survival (OS) and safety. Results: From September 13, 2021 to February 01, 2023, 12 patients were enrolled (58.0% male, median age 61 years old), and the median follow up time was 7.3 months (0.4-16.9). Seven patients completed surgery, and 5 patients were undergoing neoadjuvant therapy. The R0 resection rate was 100%, 3 patients (42.9%) achieved pCR, and 4 patients (57.1%) achieved major pathological remission (MPR). Postoperative pathology showed tumor downstaging in 5 cases after neoadjuvant therapy, with a decrease rate of 71.4%. Median OS and EFS have not been reached. The most common AEs (all grades, grade ≥3) were anemia in 1 (8.3%) and neutropenia in 1 case (8.3%). The immune-related adverse events were all grade 1 included 2 thyroid dysfunction (16.7%), 1 abnormal liver function (8.3%), and 1 of elevated blood sugar (8.3%). No grade 3 or higher immune-related AE was observed. No treatment related deaths were reported. Conclusions: According to the preliminary results, tislelizumab combined with trastuzumab and standard chemotherapy in the perioperative period of HER2-positive GC and EGJ have a good clinical benefit trend and controllable security. Clinical trial information: NCT04819971 .

Efficacy and safety of perioperative chemotherapy combined with tislelizumab and trastuzumab for HER2-positive resectable gastric/gastroesophageal junction cancer (GC/EGJC): Preliminary results of a phase 2, single-arm trial.

Chao Ding

Papers

The role of vegetation on earth bunds in mitigating soil erosion in Mollisols region of Northeast China

The effectiveness of selected vegetation communities in regulating runoff and soil loss from regraded gully banks in the Mollisol region of Northeast China

Two-dimensional information measurement method for farmland erosion groove based on non-aerial photograph of unmanned aerial vehicle

Efficacy and safety of perioperative chemotherapy combined with tislelizumab and trastuzumab for HER2-positive resectable gastric/gastroesophageal junction cancer (GC/EGJC): Preliminary results of a phase 2, single-arm trial.