Hurricane Harvey has devastated parts of southeast Texas.

Record rainfall and catastrophic flooding have created a disaster in the area, especially in Houston, the fourth-largest city in the United States. As much as 50 inches of rain could accumulate in the area by Wednesday.

At least nine people have been killed, tens of thousands are temporarily displaced and hundreds of thousands will need Federal Emergency Management Agency assistance. More than 2,000 people required water rescue. Nearly 7 million people have been affected.

If you live in southeast Texas, there's a lot you can do.

You can volunteer to help through All Hands Volunteers and Volunteer Houston. If you're able to donate blood, the Houston Chronicle recommends donating to Carter BloodCare and the South Texas Blood and Tissue Center. You can help stock the Houston Food Bank, the Food Bank of Corpus Christi and the Texas Diaper Bank. And contact the SPCA of Texas and other animal welfare organizations if you're able to help care for displaced pets and animals.

If you live anywhere else, you've got your wallet. And most experts in disaster relief will tell you that the best way you can help in a place far from where you live is to send money, not stuff.

The US Agency for International Development explains why.

"Unlike material donations, cash involves no transportation costs, shipping delays, or customs fees," the agency says. "It also enables relief organizations to spend more time providing aid by spending less time managing goods."

If you're considering donating to a charity, do your homework. Charity Navigator has a guide to the organizations operating in areas hit by Harvey.

Here are some options.

Local organizations

The ones listed above all accept donations. Check them out. You'll find some more listed below. Local groups can often be the most effective ones in relief situations.

Hurricane Harvey Relief Fund

Houston Mayor Sylvester Turner established this general fund to support those affected by the hurricane after receiving an "overwhelming number of inquiries from citizens and companies who want to help." It's administered through Greater Houston Community Foundation. Donate here.

American Red Cross

The Red Cross has been criticized at times for how it's handled past relief efforts. So it's worth a bit of research before you decide whether you're comfortable giving them your money. Former President Barack Obama seems comfortable recommending them these days.

Thank you to all the first responders and people helping each other out. That's what we do as Americans. Here's one way you can help now. https://t.co/iGfE8rAoAu — Barack Obama (@BarackObama) August 27, 2017

Regardless, the organization is on the ground in southeast Texas, helping provide shelter and services to flood victims. You can donate $10 by texting 90999 and give any amount on the Red Cross website.

GlobalGiving

The charity crowdfunding site is aiming to raise $2 million for Harvey relief. More than 9,000 people have donated nearly $800,000 as of Tuesday morning.

Here's where GlobalGiving says the money will go: "All donations to this fund will support recovery and relief efforts for Hurricane Harvey. Initially, the fund will help first responders meet survivors' immediate needs for food, fuel, clean water, hygiene products, and shelter. Once initial relief work is complete, this fund will support longer-term recovery efforts run by local, vetted organizations in the Gulf Coast."

Direct Relief

Direct Relief specializes in medical aid. It's supporting clinics and community health centers to provide care and supplies.

AmeriCares

AmeriCares is a health-focused organization. "Right now, AmeriCares is in Texas, distributing water, aid and mobilizing medical outreach with our local partners." Donate here.

Portlight

Portlight has been assisting persons with disabilities affected by Harvey, in coordination with the Texas government, the Houston mayor's office and FEMA.

The United Way of Greater Houston

The United Way of Greater Houston is collecting general funds for flood relief. You can donate by texting UWFLOOD to 41444 or by visiting their website.

Save the Children

This global charity with a reputation for good work in some of the roughest conflict zones around the world is working to setup child-friendly spaces in shelters around Texas. There's one open in San Antonio and others are slated to open in Houston on Thursday. You can donate by texting HURRICANE to 20222 or by going to their website.

Islamic Society of Greater Houston

About a dozen Houston mosques are currently housing men, women and children displaced by the storm. And not just from the Muslim community. If you'd like to support their effort, you can visit the website of the Islamic Society of Greater Houston.

This is not a comprehensive list of organizations providing aid after Hurricane Harvey. It may be updated. Consider recommending an organization in the comments below.